linux-stable.git/net/core, branch v3.16.83 Linux kernel stable tree neighbour: remove neigh_cleanup() method 2020-04-28T18:02:44+00:00 Eric Dumazet edumazet@google.com 2019-12-07T20:23:21+00:00 7ac6e0bec8ace91cac3ce0ba0e01a7e8f9efc714 commit f394722fb0d0f701119368959d7cd0ecbc46363a upstream. neigh_cleanup() has not been used for seven years, and was a wrong design. Messing with shared pointer in bond_neigh_init() without proper memory barriers would at least trigger syzbot complains eventually. It is time to remove this stuff. Fixes: b63b70d87741 ("IPoIB: Use a private hash table for path lookup in xmit path") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit f394722fb0d0f701119368959d7cd0ecbc46363a upstream.

neigh_cleanup() has not been used for seven years, and was a wrong design.

Messing with shared pointer in bond_neigh_init() without proper
memory barriers would at least trigger syzbot complains eventually.

It is time to remove this stuff.

Fixes: b63b70d87741 ("IPoIB: Use a private hash table for path lookup in xmit path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
inet: protect against too small mtu values. 2020-02-11T20:03:57+00:00 Eric Dumazet edumazet@google.com 2019-12-06T04:43:46+00:00 31664e11ce11b1bfb7507c5c5ca745ddee9cd1a3 commit 501a90c945103e8627406763dac418f20f3837b2 upstream. syzbot was once again able to crash a host by setting a very small mtu on loopback device. Let's make inetdev_valid_mtu() available in include/net/ip.h, and use it in ip_setup_cork(), so that we protect both ip_append_page() and __ip_append_data() Also add a READ_ONCE() when the device mtu is read. Pairs this lockless read with one WRITE_ONCE() in __dev_set_mtu(), even if other code paths might write over this field. Add a big comment in include/linux/netdevice.h about dev->mtu needing READ_ONCE()/WRITE_ONCE() annotations. Hopefully we will add the missing ones in followup patches. [1] refcount_t: saturated; leaking memory. WARNING: CPU: 0 PID: 9464 at lib/refcount.c:22 refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 9464 Comm: syz-executor850 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 panic+0x2e3/0x75c kernel/panic.c:221 __warn.cold+0x2f/0x3e kernel/panic.c:582 report_bug+0x289/0x300 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:174 [inline] fixup_bug arch/x86/kernel/traps.c:169 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 RIP: 0010:refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22 Code: 06 31 ff 89 de e8 c8 f5 e6 fd 84 db 0f 85 6f ff ff ff e8 7b f4 e6 fd 48 c7 c7 e0 71 4f 88 c6 05 56 a6 a4 06 01 e8 c7 a8 b7 fd <0f> 0b e9 50 ff ff ff e8 5c f4 e6 fd 0f b6 1d 3d a6 a4 06 31 ff 89 RSP: 0018:ffff88809689f550 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815e4336 RDI: ffffed1012d13e9c RBP: ffff88809689f560 R08: ffff88809c50a3c0 R09: fffffbfff15d31b1 R10: fffffbfff15d31b0 R11: ffffffff8ae98d87 R12: 0000000000000001 R13: 0000000000040100 R14: ffff888099041104 R15: ffff888218d96e40 refcount_add include/linux/refcount.h:193 [inline] skb_set_owner_w+0x2b6/0x410 net/core/sock.c:1999 sock_wmalloc+0xf1/0x120 net/core/sock.c:2096 ip_append_page+0x7ef/0x1190 net/ipv4/ip_output.c:1383 udp_sendpage+0x1c7/0x480 net/ipv4/udp.c:1276 inet_sendpage+0xdb/0x150 net/ipv4/af_inet.c:821 kernel_sendpage+0x92/0xf0 net/socket.c:3794 sock_sendpage+0x8b/0xc0 net/socket.c:936 pipe_to_sendpage+0x2da/0x3c0 fs/splice.c:458 splice_from_pipe_feed fs/splice.c:512 [inline] __splice_from_pipe+0x3ee/0x7c0 fs/splice.c:636 splice_from_pipe+0x108/0x170 fs/splice.c:671 generic_splice_sendpage+0x3c/0x50 fs/splice.c:842 do_splice_from fs/splice.c:861 [inline] direct_splice_actor+0x123/0x190 fs/splice.c:1035 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:990 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441409 Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fffb64c4f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441409 RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005 RBP: 0000000000073b8a R08: 0000000000000010 R09: 0000000000000010 R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000402180 R13: 0000000000402210 R14: 0000000000000000 R15: 0000000000000000 Kernel Offset: disabled Rebooting in 86400 seconds.. Fixes: 1470ddf7f8ce ("inet: Remove explicit write references to sk/inet in ip_append_data") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.16: - Use ACCESS_ONCE() instead of {READ,WRITE}_ONCE() - Keep using literal 68 instead of IPV4_MIN_MTU - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 501a90c945103e8627406763dac418f20f3837b2 upstream.

syzbot was once again able to crash a host by setting a very small mtu
on loopback device.

Let's make inetdev_valid_mtu() available in include/net/ip.h,
and use it in ip_setup_cork(), so that we protect both ip_append_page()
and __ip_append_data()

Also add a READ_ONCE() when the device mtu is read.

Pairs this lockless read with one WRITE_ONCE() in __dev_set_mtu(),
even if other code paths might write over this field.

Add a big comment in include/linux/netdevice.h about dev->mtu
needing READ_ONCE()/WRITE_ONCE() annotations.

Hopefully we will add the missing ones in followup patches.

[1]

refcount_t: saturated; leaking memory.
WARNING: CPU: 0 PID: 9464 at lib/refcount.c:22 refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9464 Comm: syz-executor850 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x3e kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Code: 06 31 ff 89 de e8 c8 f5 e6 fd 84 db 0f 85 6f ff ff ff e8 7b f4 e6 fd 48 c7 c7 e0 71 4f 88 c6 05 56 a6 a4 06 01 e8 c7 a8 b7 fd <0f> 0b e9 50 ff ff ff e8 5c f4 e6 fd 0f b6 1d 3d a6 a4 06 31 ff 89
RSP: 0018:ffff88809689f550 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e4336 RDI: ffffed1012d13e9c
RBP: ffff88809689f560 R08: ffff88809c50a3c0 R09: fffffbfff15d31b1
R10: fffffbfff15d31b0 R11: ffffffff8ae98d87 R12: 0000000000000001
R13: 0000000000040100 R14: ffff888099041104 R15: ffff888218d96e40
 refcount_add include/linux/refcount.h:193 [inline]
 skb_set_owner_w+0x2b6/0x410 net/core/sock.c:1999
 sock_wmalloc+0xf1/0x120 net/core/sock.c:2096
 ip_append_page+0x7ef/0x1190 net/ipv4/ip_output.c:1383
 udp_sendpage+0x1c7/0x480 net/ipv4/udp.c:1276
 inet_sendpage+0xdb/0x150 net/ipv4/af_inet.c:821
 kernel_sendpage+0x92/0xf0 net/socket.c:3794
 sock_sendpage+0x8b/0xc0 net/socket.c:936
 pipe_to_sendpage+0x2da/0x3c0 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x3ee/0x7c0 fs/splice.c:636
 splice_from_pipe+0x108/0x170 fs/splice.c:671
 generic_splice_sendpage+0x3c/0x50 fs/splice.c:842
 do_splice_from fs/splice.c:861 [inline]
 direct_splice_actor+0x123/0x190 fs/splice.c:1035
 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:990
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441409
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffb64c4f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441409
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 0000000000073b8a R08: 0000000000000010 R09: 0000000000000010
R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000402180
R13: 0000000000402210 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Fixes: 1470ddf7f8ce ("inet: Remove explicit write references to sk/inet in ip_append_data")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16:
 - Use ACCESS_ONCE() instead of {READ,WRITE}_ONCE()
 - Keep using literal 68 instead of IPV4_MIN_MTU
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
net: Fix null de-reference of device refcount 2019-11-22T15:57:29+00:00 Subash Abhinov Kasiviswanathan subashab@codeaurora.org 2019-09-10T20:02:57+00:00 c6efe293fe6f584e0f6e67308f6a8ef476492748 commit 10cc514f451a0f239aa34f91bc9dc954a9397840 upstream. In event of failure during register_netdevice, free_netdev is invoked immediately. free_netdev assumes that all the netdevice refcounts have been dropped prior to it being called and as a result frees and clears out the refcount pointer. However, this is not necessarily true as some of the operations in the NETDEV_UNREGISTER notifier handlers queue RCU callbacks for invocation after a grace period. The IPv4 callback in_dev_rcu_put tries to access the refcount after free_netdev is called which leads to a null de-reference- 44837.761523: <6> Unable to handle kernel paging request at virtual address 0000004a88287000 44837.761651: <2> pc : in_dev_finish_destroy+0x4c/0xc8 44837.761654: <2> lr : in_dev_finish_destroy+0x2c/0xc8 44837.762393: <2> Call trace: 44837.762398: <2> in_dev_finish_destroy+0x4c/0xc8 44837.762404: <2> in_dev_rcu_put+0x24/0x30 44837.762412: <2> rcu_nocb_kthread+0x43c/0x468 44837.762418: <2> kthread+0x118/0x128 44837.762424: <2> ret_from_fork+0x10/0x1c Fix this by waiting for the completion of the call_rcu() in case of register_netdevice errors. Fixes: 93ee31f14f6f ("[NET]: Fix free_netdev on register_netdev failure.") Cc: Sean Tranchetti <stranche@codeaurora.org> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 10cc514f451a0f239aa34f91bc9dc954a9397840 upstream.

In event of failure during register_netdevice, free_netdev is
invoked immediately. free_netdev assumes that all the netdevice
refcounts have been dropped prior to it being called and as a
result frees and clears out the refcount pointer.

However, this is not necessarily true as some of the operations
in the NETDEV_UNREGISTER notifier handlers queue RCU callbacks for
invocation after a grace period. The IPv4 callback in_dev_rcu_put
tries to access the refcount after free_netdev is called which
leads to a null de-reference-

44837.761523:   <6> Unable to handle kernel paging request at
                    virtual address 0000004a88287000
44837.761651:   <2> pc : in_dev_finish_destroy+0x4c/0xc8
44837.761654:   <2> lr : in_dev_finish_destroy+0x2c/0xc8
44837.762393:   <2> Call trace:
44837.762398:   <2>  in_dev_finish_destroy+0x4c/0xc8
44837.762404:   <2>  in_dev_rcu_put+0x24/0x30
44837.762412:   <2>  rcu_nocb_kthread+0x43c/0x468
44837.762418:   <2>  kthread+0x118/0x128
44837.762424:   <2>  ret_from_fork+0x10/0x1c

Fix this by waiting for the completion of the call_rcu() in
case of register_netdevice errors.

Fixes: 93ee31f14f6f ("[NET]: Fix free_netdev on register_netdev failure.")
Cc: Sean Tranchetti <stranche@codeaurora.org>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
net: fix ifindex collision during namespace removal 2019-11-22T15:57:08+00:00 Jiri Pirko jiri@mellanox.com 2019-07-28T12:56:36+00:00 72a89066640b9b5b34d68a2e7cb199209dba7e95 commit 55b40dbf0e76b4bfb9d8b3a16a0208640a9a45df upstream. Commit aca51397d014 ("netns: Fix arbitrary net_device-s corruptions on net_ns stop.") introduced a possibility to hit a BUG in case device is returning back to init_net and two following conditions are met: 1) dev->ifindex value is used in a name of another "dev%d" device in init_net. 2) dev->name is used by another device in init_net. Under real life circumstances this is hard to get. Therefore this has been present happily for over 10 years. To reproduce: $ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 86:89:3f:86:61:29 brd ff:ff:ff:ff:ff:ff 3: enp0s2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff $ ip netns add ns1 $ ip -n ns1 link add dummy1ns1 type dummy $ ip -n ns1 link add dummy2ns1 type dummy $ ip link set enp0s2 netns ns1 $ ip -n ns1 link set enp0s2 name dummy0 [ 100.858894] virtio_net virtio0 dummy0: renamed from enp0s2 $ ip link add dev4 type dummy $ ip -n ns1 a 1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: dummy1ns1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 16:63:4c:38:3e:ff brd ff:ff:ff:ff:ff:ff 3: dummy2ns1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether aa:9e:86:dd:6b:5d brd ff:ff:ff:ff:ff:ff 4: dummy0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff $ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 86:89:3f:86:61:29 brd ff:ff:ff:ff:ff:ff 4: dev4: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether 5a:e1:4a:b6:ec:f8 brd ff:ff:ff:ff:ff:ff $ ip netns del ns1 [ 158.717795] default_device_exit: failed to move dummy0 to init_net: -17 [ 158.719316] ------------[ cut here ]------------ [ 158.720591] kernel BUG at net/core/dev.c:9824! [ 158.722260] invalid opcode: 0000 [#1] SMP KASAN PTI [ 158.723728] CPU: 0 PID: 56 Comm: kworker/u2:1 Not tainted 5.3.0-rc1+ #18 [ 158.725422] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014 [ 158.727508] Workqueue: netns cleanup_net [ 158.728915] RIP: 0010:default_device_exit.cold+0x1d/0x1f [ 158.730683] Code: 84 e8 18 c9 3e fe 0f 0b e9 70 90 ff ff e8 36 e4 52 fe 89 d9 4c 89 e2 48 c7 c6 80 d6 25 84 48 c7 c7 20 c0 25 84 e8 f4 c8 3e [ 158.736854] RSP: 0018:ffff8880347e7b90 EFLAGS: 00010282 [ 158.738752] RAX: 000000000000003b RBX: 00000000ffffffef RCX: 0000000000000000 [ 158.741369] RDX: 0000000000000000 RSI: ffffffff8128013d RDI: ffffed10068fcf64 [ 158.743418] RBP: ffff888033550170 R08: 000000000000003b R09: fffffbfff0b94b9c [ 158.745626] R10: fffffbfff0b94b9b R11: ffffffff85ca5cdf R12: ffff888032f28000 [ 158.748405] R13: dffffc0000000000 R14: ffff8880335501b8 R15: 1ffff110068fcf72 [ 158.750638] FS: 0000000000000000(0000) GS:ffff888036000000(0000) knlGS:0000000000000000 [ 158.752944] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 158.755245] CR2: 00007fe8b45d21d0 CR3: 00000000340b4005 CR4: 0000000000360ef0 [ 158.757654] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 158.760012] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 158.762758] Call Trace: [ 158.763882] ? dev_change_net_namespace+0xbb0/0xbb0 [ 158.766148] ? devlink_nl_cmd_set_doit+0x520/0x520 [ 158.768034] ? dev_change_net_namespace+0xbb0/0xbb0 [ 158.769870] ops_exit_list.isra.0+0xa8/0x150 [ 158.771544] cleanup_net+0x446/0x8f0 [ 158.772945] ? unregister_pernet_operations+0x4a0/0x4a0 [ 158.775294] process_one_work+0xa1a/0x1740 [ 158.776896] ? pwq_dec_nr_in_flight+0x310/0x310 [ 158.779143] ? do_raw_spin_lock+0x11b/0x280 [ 158.780848] worker_thread+0x9e/0x1060 [ 158.782500] ? process_one_work+0x1740/0x1740 [ 158.784454] kthread+0x31b/0x420 [ 158.786082] ? __kthread_create_on_node+0x3f0/0x3f0 [ 158.788286] ret_from_fork+0x3a/0x50 [ 158.789871] ---[ end trace defd6c657c71f936 ]--- [ 158.792273] RIP: 0010:default_device_exit.cold+0x1d/0x1f [ 158.795478] Code: 84 e8 18 c9 3e fe 0f 0b e9 70 90 ff ff e8 36 e4 52 fe 89 d9 4c 89 e2 48 c7 c6 80 d6 25 84 48 c7 c7 20 c0 25 84 e8 f4 c8 3e [ 158.804854] RSP: 0018:ffff8880347e7b90 EFLAGS: 00010282 [ 158.807865] RAX: 000000000000003b RBX: 00000000ffffffef RCX: 0000000000000000 [ 158.811794] RDX: 0000000000000000 RSI: ffffffff8128013d RDI: ffffed10068fcf64 [ 158.816652] RBP: ffff888033550170 R08: 000000000000003b R09: fffffbfff0b94b9c [ 158.820930] R10: fffffbfff0b94b9b R11: ffffffff85ca5cdf R12: ffff888032f28000 [ 158.825113] R13: dffffc0000000000 R14: ffff8880335501b8 R15: 1ffff110068fcf72 [ 158.829899] FS: 0000000000000000(0000) GS:ffff888036000000(0000) knlGS:0000000000000000 [ 158.834923] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 158.838164] CR2: 00007fe8b45d21d0 CR3: 00000000340b4005 CR4: 0000000000360ef0 [ 158.841917] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 158.845149] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Fix this by checking if a device with the same name exists in init_net and fallback to original code - dev%d to allocate name - in case it does. This was found using syzkaller. Fixes: aca51397d014 ("netns: Fix arbitrary net_device-s corruptions on net_ns stop.") Signed-off-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 55b40dbf0e76b4bfb9d8b3a16a0208640a9a45df upstream.

Commit aca51397d014 ("netns: Fix arbitrary net_device-s corruptions
on net_ns stop.") introduced a possibility to hit a BUG in case device
is returning back to init_net and two following conditions are met:
1) dev->ifindex value is used in a name of another "dev%d"
   device in init_net.
2) dev->name is used by another device in init_net.

Under real life circumstances this is hard to get. Therefore this has
been present happily for over 10 years. To reproduce:

$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 86:89:3f:86:61:29 brd ff:ff:ff:ff:ff:ff
3: enp0s2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff
$ ip netns add ns1
$ ip -n ns1 link add dummy1ns1 type dummy
$ ip -n ns1 link add dummy2ns1 type dummy
$ ip link set enp0s2 netns ns1
$ ip -n ns1 link set enp0s2 name dummy0
[  100.858894] virtio_net virtio0 dummy0: renamed from enp0s2
$ ip link add dev4 type dummy
$ ip -n ns1 a
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: dummy1ns1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 16:63:4c:38:3e:ff brd ff:ff:ff:ff:ff:ff
3: dummy2ns1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether aa:9e:86:dd:6b:5d brd ff:ff:ff:ff:ff:ff
4: dummy0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff
$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 86:89:3f:86:61:29 brd ff:ff:ff:ff:ff:ff
4: dev4: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 5a:e1:4a:b6:ec:f8 brd ff:ff:ff:ff:ff:ff
$ ip netns del ns1
[  158.717795] default_device_exit: failed to move dummy0 to init_net: -17
[  158.719316] ------------[ cut here ]------------
[  158.720591] kernel BUG at net/core/dev.c:9824!
[  158.722260] invalid opcode: 0000 [#1] SMP KASAN PTI
[  158.723728] CPU: 0 PID: 56 Comm: kworker/u2:1 Not tainted 5.3.0-rc1+ #18
[  158.725422] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
[  158.727508] Workqueue: netns cleanup_net
[  158.728915] RIP: 0010:default_device_exit.cold+0x1d/0x1f
[  158.730683] Code: 84 e8 18 c9 3e fe 0f 0b e9 70 90 ff ff e8 36 e4 52 fe 89 d9 4c 89 e2 48 c7 c6 80 d6 25 84 48 c7 c7 20 c0 25 84 e8 f4 c8 3e
[  158.736854] RSP: 0018:ffff8880347e7b90 EFLAGS: 00010282
[  158.738752] RAX: 000000000000003b RBX: 00000000ffffffef RCX: 0000000000000000
[  158.741369] RDX: 0000000000000000 RSI: ffffffff8128013d RDI: ffffed10068fcf64
[  158.743418] RBP: ffff888033550170 R08: 000000000000003b R09: fffffbfff0b94b9c
[  158.745626] R10: fffffbfff0b94b9b R11: ffffffff85ca5cdf R12: ffff888032f28000
[  158.748405] R13: dffffc0000000000 R14: ffff8880335501b8 R15: 1ffff110068fcf72
[  158.750638] FS:  0000000000000000(0000) GS:ffff888036000000(0000) knlGS:0000000000000000
[  158.752944] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  158.755245] CR2: 00007fe8b45d21d0 CR3: 00000000340b4005 CR4: 0000000000360ef0
[  158.757654] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  158.760012] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  158.762758] Call Trace:
[  158.763882]  ? dev_change_net_namespace+0xbb0/0xbb0
[  158.766148]  ? devlink_nl_cmd_set_doit+0x520/0x520
[  158.768034]  ? dev_change_net_namespace+0xbb0/0xbb0
[  158.769870]  ops_exit_list.isra.0+0xa8/0x150
[  158.771544]  cleanup_net+0x446/0x8f0
[  158.772945]  ? unregister_pernet_operations+0x4a0/0x4a0
[  158.775294]  process_one_work+0xa1a/0x1740
[  158.776896]  ? pwq_dec_nr_in_flight+0x310/0x310
[  158.779143]  ? do_raw_spin_lock+0x11b/0x280
[  158.780848]  worker_thread+0x9e/0x1060
[  158.782500]  ? process_one_work+0x1740/0x1740
[  158.784454]  kthread+0x31b/0x420
[  158.786082]  ? __kthread_create_on_node+0x3f0/0x3f0
[  158.788286]  ret_from_fork+0x3a/0x50
[  158.789871] ---[ end trace defd6c657c71f936 ]---
[  158.792273] RIP: 0010:default_device_exit.cold+0x1d/0x1f
[  158.795478] Code: 84 e8 18 c9 3e fe 0f 0b e9 70 90 ff ff e8 36 e4 52 fe 89 d9 4c 89 e2 48 c7 c6 80 d6 25 84 48 c7 c7 20 c0 25 84 e8 f4 c8 3e
[  158.804854] RSP: 0018:ffff8880347e7b90 EFLAGS: 00010282
[  158.807865] RAX: 000000000000003b RBX: 00000000ffffffef RCX: 0000000000000000
[  158.811794] RDX: 0000000000000000 RSI: ffffffff8128013d RDI: ffffed10068fcf64
[  158.816652] RBP: ffff888033550170 R08: 000000000000003b R09: fffffbfff0b94b9c
[  158.820930] R10: fffffbfff0b94b9b R11: ffffffff85ca5cdf R12: ffff888032f28000
[  158.825113] R13: dffffc0000000000 R14: ffff8880335501b8 R15: 1ffff110068fcf72
[  158.829899] FS:  0000000000000000(0000) GS:ffff888036000000(0000) knlGS:0000000000000000
[  158.834923] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  158.838164] CR2: 00007fe8b45d21d0 CR3: 00000000340b4005 CR4: 0000000000360ef0
[  158.841917] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  158.845149] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Fix this by checking if a device with the same name exists in init_net
and fallback to original code - dev%d to allocate name - in case it does.

This was found using syzkaller.

Fixes: aca51397d014 ("netns: Fix arbitrary net_device-s corruptions on net_ns stop.")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
net: neigh: fix multiple neigh timer scheduling 2019-10-31T22:15:03+00:00 Lorenzo Bianconi lorenzo.bianconi@redhat.com 2019-07-14T21:36:11+00:00 6048bf226c595c0c5dbc80c736ae2e4275bb7e34 commit 071c37983d99da07797294ea78e9da1a6e287144 upstream. Neigh timer can be scheduled multiple times from userspace adding multiple neigh entries and forcing the neigh timer scheduling passing NTF_USE in the netlink requests. This will result in a refcount leak and in the following dump stack: [ 32.465295] NEIGH: BUG, double timer add, state is 8 [ 32.465308] CPU: 0 PID: 416 Comm: double_timer_ad Not tainted 5.2.0+ #65 [ 32.465311] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-2.fc30 04/01/2014 [ 32.465313] Call Trace: [ 32.465318] dump_stack+0x7c/0xc0 [ 32.465323] __neigh_event_send+0x20c/0x880 [ 32.465326] ? ___neigh_create+0x846/0xfb0 [ 32.465329] ? neigh_lookup+0x2a9/0x410 [ 32.465332] ? neightbl_fill_info.constprop.0+0x800/0x800 [ 32.465334] neigh_add+0x4f8/0x5e0 [ 32.465337] ? neigh_xmit+0x620/0x620 [ 32.465341] ? find_held_lock+0x85/0xa0 [ 32.465345] rtnetlink_rcv_msg+0x204/0x570 [ 32.465348] ? rtnl_dellink+0x450/0x450 [ 32.465351] ? mark_held_locks+0x90/0x90 [ 32.465354] ? match_held_lock+0x1b/0x230 [ 32.465357] netlink_rcv_skb+0xc4/0x1d0 [ 32.465360] ? rtnl_dellink+0x450/0x450 [ 32.465363] ? netlink_ack+0x420/0x420 [ 32.465366] ? netlink_deliver_tap+0x115/0x560 [ 32.465369] ? __alloc_skb+0xc9/0x2f0 [ 32.465372] netlink_unicast+0x270/0x330 [ 32.465375] ? netlink_attachskb+0x2f0/0x2f0 [ 32.465378] netlink_sendmsg+0x34f/0x5a0 [ 32.465381] ? netlink_unicast+0x330/0x330 [ 32.465385] ? move_addr_to_kernel.part.0+0x20/0x20 [ 32.465388] ? netlink_unicast+0x330/0x330 [ 32.465391] sock_sendmsg+0x91/0xa0 [ 32.465394] ___sys_sendmsg+0x407/0x480 [ 32.465397] ? copy_msghdr_from_user+0x200/0x200 [ 32.465401] ? _raw_spin_unlock_irqrestore+0x37/0x40 [ 32.465404] ? lockdep_hardirqs_on+0x17d/0x250 [ 32.465407] ? __wake_up_common_lock+0xcb/0x110 [ 32.465410] ? __wake_up_common+0x230/0x230 [ 32.465413] ? netlink_bind+0x3e1/0x490 [ 32.465416] ? netlink_setsockopt+0x540/0x540 [ 32.465420] ? __fget_light+0x9c/0xf0 [ 32.465423] ? sockfd_lookup_light+0x8c/0xb0 [ 32.465426] __sys_sendmsg+0xa5/0x110 [ 32.465429] ? __ia32_sys_shutdown+0x30/0x30 [ 32.465432] ? __fd_install+0xe1/0x2c0 [ 32.465435] ? lockdep_hardirqs_off+0xb5/0x100 [ 32.465438] ? mark_held_locks+0x24/0x90 [ 32.465441] ? do_syscall_64+0xf/0x270 [ 32.465444] do_syscall_64+0x63/0x270 [ 32.465448] entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix the issue unscheduling neigh_timer if selected entry is in 'IN_TIMER' receiving a netlink request with NTF_USE flag set Reported-by: Marek Majkowski <marek@cloudflare.com> Fixes: 0c5c2d308906 ("neigh: Allow for user space users of the neighbour table") Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com> Reviewed-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 071c37983d99da07797294ea78e9da1a6e287144 upstream.

Neigh timer can be scheduled multiple times from userspace adding
multiple neigh entries and forcing the neigh timer scheduling passing
NTF_USE in the netlink requests.
This will result in a refcount leak and in the following dump stack:

[   32.465295] NEIGH: BUG, double timer add, state is 8
[   32.465308] CPU: 0 PID: 416 Comm: double_timer_ad Not tainted 5.2.0+ #65
[   32.465311] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-2.fc30 04/01/2014
[   32.465313] Call Trace:
[   32.465318]  dump_stack+0x7c/0xc0
[   32.465323]  __neigh_event_send+0x20c/0x880
[   32.465326]  ? ___neigh_create+0x846/0xfb0
[   32.465329]  ? neigh_lookup+0x2a9/0x410
[   32.465332]  ? neightbl_fill_info.constprop.0+0x800/0x800
[   32.465334]  neigh_add+0x4f8/0x5e0
[   32.465337]  ? neigh_xmit+0x620/0x620
[   32.465341]  ? find_held_lock+0x85/0xa0
[   32.465345]  rtnetlink_rcv_msg+0x204/0x570
[   32.465348]  ? rtnl_dellink+0x450/0x450
[   32.465351]  ? mark_held_locks+0x90/0x90
[   32.465354]  ? match_held_lock+0x1b/0x230
[   32.465357]  netlink_rcv_skb+0xc4/0x1d0
[   32.465360]  ? rtnl_dellink+0x450/0x450
[   32.465363]  ? netlink_ack+0x420/0x420
[   32.465366]  ? netlink_deliver_tap+0x115/0x560
[   32.465369]  ? __alloc_skb+0xc9/0x2f0
[   32.465372]  netlink_unicast+0x270/0x330
[   32.465375]  ? netlink_attachskb+0x2f0/0x2f0
[   32.465378]  netlink_sendmsg+0x34f/0x5a0
[   32.465381]  ? netlink_unicast+0x330/0x330
[   32.465385]  ? move_addr_to_kernel.part.0+0x20/0x20
[   32.465388]  ? netlink_unicast+0x330/0x330
[   32.465391]  sock_sendmsg+0x91/0xa0
[   32.465394]  ___sys_sendmsg+0x407/0x480
[   32.465397]  ? copy_msghdr_from_user+0x200/0x200
[   32.465401]  ? _raw_spin_unlock_irqrestore+0x37/0x40
[   32.465404]  ? lockdep_hardirqs_on+0x17d/0x250
[   32.465407]  ? __wake_up_common_lock+0xcb/0x110
[   32.465410]  ? __wake_up_common+0x230/0x230
[   32.465413]  ? netlink_bind+0x3e1/0x490
[   32.465416]  ? netlink_setsockopt+0x540/0x540
[   32.465420]  ? __fget_light+0x9c/0xf0
[   32.465423]  ? sockfd_lookup_light+0x8c/0xb0
[   32.465426]  __sys_sendmsg+0xa5/0x110
[   32.465429]  ? __ia32_sys_shutdown+0x30/0x30
[   32.465432]  ? __fd_install+0xe1/0x2c0
[   32.465435]  ? lockdep_hardirqs_off+0xb5/0x100
[   32.465438]  ? mark_held_locks+0x24/0x90
[   32.465441]  ? do_syscall_64+0xf/0x270
[   32.465444]  do_syscall_64+0x63/0x270
[   32.465448]  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fix the issue unscheduling neigh_timer if selected entry is in 'IN_TIMER'
receiving a netlink request with NTF_USE flag set

Reported-by: Marek Majkowski <marek@cloudflare.com>
Fixes: 0c5c2d308906 ("neigh: Allow for user space users of the neighbour table")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
neigh: fix use-after-free read in pneigh_get_next 2019-10-05T15:20:00+00:00 Eric Dumazet edumazet@google.com 2019-06-15T23:28:48+00:00 1bad37d8251ba2c47ad91913a8a51f52ffe2874b commit f3e92cb8e2eb8c27d109e6fd73d3a69a8c09e288 upstream. Nine years ago, I added RCU handling to neighbours, not pneighbours. (pneigh are not commonly used) Unfortunately I missed that /proc dump operations would use a common entry and exit point : neigh_seq_start() and neigh_seq_stop() We need to read_lock(tbl->lock) or risk use-after-free while iterating the pneigh structures. We might later convert pneigh to RCU and revert this patch. sysbot reported : BUG: KASAN: use-after-free in pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:3158 Read of size 8 at addr ffff888097f2a700 by task syz-executor.0/9825 CPU: 1 PID: 9825 Comm: syz-executor.0 Not tainted 5.2.0-rc4+ #32 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 kasan_report+0x12/0x20 mm/kasan/common.c:614 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:3158 neigh_seq_next+0xdb/0x210 net/core/neighbour.c:3240 seq_read+0x9cf/0x1110 fs/seq_file.c:258 proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:221 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:359 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:414 do_splice_to+0x127/0x180 fs/splice.c:877 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954 do_splice_direct+0x1da/0x2a0 fs/splice.c:1063 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4592c9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f4aab51dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004592c9 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000080000000 R11: 0000000000000246 R12: 00007f4aab51e6d4 R13: 00000000004c689d R14: 00000000004db828 R15: 00000000ffffffff Allocated by task 9827: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:489 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503 __do_kmalloc mm/slab.c:3660 [inline] __kmalloc+0x15c/0x740 mm/slab.c:3669 kmalloc include/linux/slab.h:552 [inline] pneigh_lookup+0x19c/0x4a0 net/core/neighbour.c:731 arp_req_set_public net/ipv4/arp.c:1010 [inline] arp_req_set+0x613/0x720 net/ipv4/arp.c:1026 arp_ioctl+0x652/0x7f0 net/ipv4/arp.c:1226 inet_ioctl+0x2a0/0x340 net/ipv4/af_inet.c:926 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1043 sock_ioctl+0x3ed/0x780 net/socket.c:1194 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9824: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 __cache_free mm/slab.c:3432 [inline] kfree+0xcf/0x220 mm/slab.c:3755 pneigh_ifdown_and_unlock net/core/neighbour.c:812 [inline] __neigh_ifdown+0x236/0x2f0 net/core/neighbour.c:356 neigh_ifdown+0x20/0x30 net/core/neighbour.c:372 arp_ifdown+0x1d/0x21 net/ipv4/arp.c:1274 inetdev_destroy net/ipv4/devinet.c:319 [inline] inetdev_event+0xa14/0x11f0 net/ipv4/devinet.c:1544 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 __raw_notifier_call_chain kernel/notifier.c:396 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749 call_netdevice_notifiers_extack net/core/dev.c:1761 [inline] call_netdevice_notifiers net/core/dev.c:1775 [inline] rollback_registered_many+0x9b9/0xfc0 net/core/dev.c:8178 rollback_registered+0x109/0x1d0 net/core/dev.c:8220 unregister_netdevice_queue net/core/dev.c:9267 [inline] unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9260 unregister_netdevice include/linux/netdevice.h:2631 [inline] __tun_detach+0xd8a/0x1040 drivers/net/tun.c:724 tun_detach drivers/net/tun.c:741 [inline] tun_chr_close+0xe0/0x180 drivers/net/tun.c:3451 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:185 [inline] exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888097f2a700 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes inside of 64-byte region [ffff888097f2a700, ffff888097f2a740) The buggy address belongs to the page: page:ffffea00025fca80 refcount:1 mapcount:0 mapping:ffff8880aa400340 index:0x0 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea000250d548 ffffea00025726c8 ffff8880aa400340 raw: 0000000000000000 ffff888097f2a000 0000000100000020 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888097f2a600: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ffff888097f2a680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff888097f2a700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff888097f2a780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888097f2a800: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit f3e92cb8e2eb8c27d109e6fd73d3a69a8c09e288 upstream.

Nine years ago, I added RCU handling to neighbours, not pneighbours.
(pneigh are not commonly used)

Unfortunately I missed that /proc dump operations would use a
common entry and exit point : neigh_seq_start() and neigh_seq_stop()

We need to read_lock(tbl->lock) or risk use-after-free while
iterating the pneigh structures.

We might later convert pneigh to RCU and revert this patch.

sysbot reported :

BUG: KASAN: use-after-free in pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:3158
Read of size 8 at addr ffff888097f2a700 by task syz-executor.0/9825

CPU: 1 PID: 9825 Comm: syz-executor.0 Not tainted 5.2.0-rc4+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 pneigh_get_next.isra.0+0x24b/0x280 net/core/neighbour.c:3158
 neigh_seq_next+0xdb/0x210 net/core/neighbour.c:3240
 seq_read+0x9cf/0x1110 fs/seq_file.c:258
 proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:221
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_loop_readv_writev fs/read_write.c:701 [inline]
 do_iter_read+0x4a4/0x660 fs/read_write.c:935
 vfs_readv+0xf0/0x160 fs/read_write.c:997
 kernel_readv fs/splice.c:359 [inline]
 default_file_splice_read+0x475/0x890 fs/splice.c:414
 do_splice_to+0x127/0x180 fs/splice.c:877
 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1063
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4592c9
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4aab51dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004592c9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000246 R12: 00007f4aab51e6d4
R13: 00000000004c689d R14: 00000000004db828 R15: 00000000ffffffff

Allocated by task 9827:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
 __do_kmalloc mm/slab.c:3660 [inline]
 __kmalloc+0x15c/0x740 mm/slab.c:3669
 kmalloc include/linux/slab.h:552 [inline]
 pneigh_lookup+0x19c/0x4a0 net/core/neighbour.c:731
 arp_req_set_public net/ipv4/arp.c:1010 [inline]
 arp_req_set+0x613/0x720 net/ipv4/arp.c:1026
 arp_ioctl+0x652/0x7f0 net/ipv4/arp.c:1226
 inet_ioctl+0x2a0/0x340 net/ipv4/af_inet.c:926
 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1043
 sock_ioctl+0x3ed/0x780 net/socket.c:1194
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9824:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kfree+0xcf/0x220 mm/slab.c:3755
 pneigh_ifdown_and_unlock net/core/neighbour.c:812 [inline]
 __neigh_ifdown+0x236/0x2f0 net/core/neighbour.c:356
 neigh_ifdown+0x20/0x30 net/core/neighbour.c:372
 arp_ifdown+0x1d/0x21 net/ipv4/arp.c:1274
 inetdev_destroy net/ipv4/devinet.c:319 [inline]
 inetdev_event+0xa14/0x11f0 net/ipv4/devinet.c:1544
 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749
 call_netdevice_notifiers_extack net/core/dev.c:1761 [inline]
 call_netdevice_notifiers net/core/dev.c:1775 [inline]
 rollback_registered_many+0x9b9/0xfc0 net/core/dev.c:8178
 rollback_registered+0x109/0x1d0 net/core/dev.c:8220
 unregister_netdevice_queue net/core/dev.c:9267 [inline]
 unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9260
 unregister_netdevice include/linux/netdevice.h:2631 [inline]
 __tun_detach+0xd8a/0x1040 drivers/net/tun.c:724
 tun_detach drivers/net/tun.c:741 [inline]
 tun_chr_close+0xe0/0x180 drivers/net/tun.c:3451
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:185 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888097f2a700
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
 64-byte region [ffff888097f2a700, ffff888097f2a740)
The buggy address belongs to the page:
page:ffffea00025fca80 refcount:1 mapcount:0 mapping:ffff8880aa400340 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000250d548 ffffea00025726c8 ffff8880aa400340
raw: 0000000000000000 ffff888097f2a000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888097f2a600: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff888097f2a680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888097f2a700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                   ^
 ffff888097f2a780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888097f2a800: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc

Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
pktgen: do not sleep with the thread lock held. 2019-10-05T15:19:54+00:00 Paolo Abeni pabeni@redhat.com 2019-06-06T13:45:03+00:00 55a1be16e1a8f04a39391e10b70d914e7e588e6e commit 720f1de4021f09898b8c8443f3b3e995991b6e3a upstream. Currently, the process issuing a "start" command on the pktgen procfs interface, acquires the pktgen thread lock and never release it, until all pktgen threads are completed. The above can blocks indefinitely any other pktgen command and any (even unrelated) netdevice removal - as the pktgen netdev notifier acquires the same lock. The issue is demonstrated by the following script, reported by Matteo: ip -b - <<'EOF' link add type dummy link add type veth link set dummy0 up EOF modprobe pktgen echo reset >/proc/net/pktgen/pgctrl { echo rem_device_all echo add_device dummy0 } >/proc/net/pktgen/kpktgend_0 echo count 0 >/proc/net/pktgen/dummy0 echo start >/proc/net/pktgen/pgctrl & sleep 1 rmmod veth Fix the above releasing the thread lock around the sleep call. Additionally we must prevent racing with forcefull rmmod - as the thread lock no more protects from them. Instead, acquire a self-reference before waiting for any thread. As a side effect, running rmmod pktgen while some thread is running now fails with "module in use" error, before this patch such command hanged indefinitely. Note: the issue predates the commit reported in the fixes tag, but this fix can't be applied before the mentioned commit. v1 -> v2: - no need to check for thread existence after flipping the lock, pktgen threads are freed only at net exit time - Fixes: 6146e6a43b35 ("[PKTGEN]: Removes thread_{un,}lock() macros.") Reported-and-tested-by: Matteo Croce <mcroce@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 720f1de4021f09898b8c8443f3b3e995991b6e3a upstream.

Currently, the process issuing a "start" command on the pktgen procfs
interface, acquires the pktgen thread lock and never release it, until
all pktgen threads are completed. The above can blocks indefinitely any
other pktgen command and any (even unrelated) netdevice removal - as
the pktgen netdev notifier acquires the same lock.

The issue is demonstrated by the following script, reported by Matteo:

ip -b - <<'EOF'
	link add type dummy
	link add type veth
	link set dummy0 up
EOF
modprobe pktgen
echo reset >/proc/net/pktgen/pgctrl
{
	echo rem_device_all
	echo add_device dummy0
} >/proc/net/pktgen/kpktgend_0
echo count 0 >/proc/net/pktgen/dummy0
echo start >/proc/net/pktgen/pgctrl &
sleep 1
rmmod veth

Fix the above releasing the thread lock around the sleep call.

Additionally we must prevent racing with forcefull rmmod - as the
thread lock no more protects from them. Instead, acquire a self-reference
before waiting for any thread. As a side effect, running

rmmod pktgen

while some thread is running now fails with "module in use" error,
before this patch such command hanged indefinitely.

Note: the issue predates the commit reported in the fixes tag, but
this fix can't be applied before the mentioned commit.

v1 -> v2:
 - no need to check for thread existence after flipping the lock,
   pktgen threads are freed only at net exit time
 -

Fixes: 6146e6a43b35 ("[PKTGEN]: Removes thread_{un,}lock() macros.")
Reported-and-tested-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
net-gro: fix use-after-free read in napi_gro_frags() 2019-10-05T15:19:51+00:00 Eric Dumazet edumazet@google.com 2019-05-29T22:36:10+00:00 f41184b4ba5bbf98b8eecae2a16fca34a669376f commit a4270d6795b0580287453ea55974d948393e66ef upstream. If a network driver provides to napi_gro_frags() an skb with a page fragment of exactly 14 bytes, the call to gro_pull_from_frag0() will 'consume' the fragment by calling skb_frag_unref(skb, 0), and the page might be freed and reused. Reading eth->h_proto at the end of napi_frags_skb() might read mangled data, or crash under specific debugging features. BUG: KASAN: use-after-free in napi_frags_skb net/core/dev.c:5833 [inline] BUG: KASAN: use-after-free in napi_gro_frags+0xc6f/0xd10 net/core/dev.c:5841 Read of size 2 at addr ffff88809366840c by task syz-executor599/8957 CPU: 1 PID: 8957 Comm: syz-executor599 Not tainted 5.2.0-rc1+ #32 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 kasan_report+0x12/0x20 mm/kasan/common.c:614 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:142 napi_frags_skb net/core/dev.c:5833 [inline] napi_gro_frags+0xc6f/0xd10 net/core/dev.c:5841 tun_get_user+0x2f3c/0x3ff0 drivers/net/tun.c:1991 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2037 call_write_iter include/linux/fs.h:1872 [inline] do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693 do_iter_write fs/read_write.c:970 [inline] do_iter_write+0x184/0x610 fs/read_write.c:951 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015 do_writev+0x15b/0x330 fs/read_write.c:1058 Fixes: a50e233c50db ("net-gro: restore frag0 optimization") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a4270d6795b0580287453ea55974d948393e66ef upstream.

If a network driver provides to napi_gro_frags() an
skb with a page fragment of exactly 14 bytes, the call
to gro_pull_from_frag0() will 'consume' the fragment
by calling skb_frag_unref(skb, 0), and the page might
be freed and reused.

Reading eth->h_proto at the end of napi_frags_skb() might
read mangled data, or crash under specific debugging features.

BUG: KASAN: use-after-free in napi_frags_skb net/core/dev.c:5833 [inline]
BUG: KASAN: use-after-free in napi_gro_frags+0xc6f/0xd10 net/core/dev.c:5841
Read of size 2 at addr ffff88809366840c by task syz-executor599/8957

CPU: 1 PID: 8957 Comm: syz-executor599 Not tainted 5.2.0-rc1+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:142
 napi_frags_skb net/core/dev.c:5833 [inline]
 napi_gro_frags+0xc6f/0xd10 net/core/dev.c:5841
 tun_get_user+0x2f3c/0x3ff0 drivers/net/tun.c:1991
 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2037
 call_write_iter include/linux/fs.h:1872 [inline]
 do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x184/0x610 fs/read_write.c:951
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015
 do_writev+0x15b/0x330 fs/read_write.c:1058

Fixes: a50e233c50db ("net-gro: restore frag0 optimization")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
net-sysfs: call dev_hold if kobject_init_and_add success 2019-08-13T11:38:48+00:00 YueHaibing yuehaibing@huawei.com 2019-03-19T02:16:53+00:00 1b75034a1bb506abcabb2c2f9d7360020a7e2c42 commit a3e23f719f5c4a38ffb3d30c8d7632a4ed8ccd9e upstream. In netdev_queue_add_kobject and rx_queue_add_kobject, if sysfs_create_group failed, kobject_put will call netdev_queue_release to decrease dev refcont, however dev_hold has not be called. So we will see this while unregistering dev: unregister_netdevice: waiting for bcsh0 to become free. Usage count = -1 Reported-by: Hulk Robot <hulkci@huawei.com> Fixes: d0d668371679 ("net: don't decrement kobj reference count on init failure") Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a3e23f719f5c4a38ffb3d30c8d7632a4ed8ccd9e upstream.

In netdev_queue_add_kobject and rx_queue_add_kobject,
if sysfs_create_group failed, kobject_put will call
netdev_queue_release to decrease dev refcont, however
dev_hold has not be called. So we will see this while
unregistering dev:

unregister_netdevice: waiting for bcsh0 to become free. Usage count = -1

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: d0d668371679 ("net: don't decrement kobj reference count on init failure")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
netns: provide pure entropy for net_hash_mix() 2019-07-09T21:04:22+00:00 Eric Dumazet edumazet@google.com 2019-03-27T15:21:30+00:00 188da790e1f4d164bcfdea486e91fd47e1ba59c5 commit 355b98553789b646ed97ad801a619ff898471b92 upstream. net_hash_mix() currently uses kernel address of a struct net, and is used in many places that could be used to reveal this address to a patient attacker, thus defeating KASLR, for the typical case (initial net namespace, &init_net is not dynamically allocated) I believe the original implementation tried to avoid spending too many cycles in this function, but security comes first. Also provide entropy regardless of CONFIG_NET_NS. Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Amit Klein <aksecurity@gmail.com> Reported-by: Benny Pinkas <benny@pinkas.net> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 355b98553789b646ed97ad801a619ff898471b92 upstream.

net_hash_mix() currently uses kernel address of a struct net,
and is used in many places that could be used to reveal this
address to a patient attacker, thus defeating KASLR, for
the typical case (initial net namespace, &init_net is
not dynamically allocated)

I believe the original implementation tried to avoid spending
too many cycles in this function, but security comes first.

Also provide entropy regardless of CONFIG_NET_NS.

Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reported-by: Benny Pinkas <benny@pinkas.net>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>