linux-stable.git/net/llc, branch v5.4 Linux kernel stable tree net: silence KCSAN warnings around sk_add_backlog() calls 2019-10-10T04:42:59+00:00 Eric Dumazet edumazet@google.com 2019-10-09T22:21:13+00:00 8265792bf8871acc2d00fd03883d830e2249d395 sk_add_backlog() callers usually read sk->sk_rcvbuf without owning the socket lock. This means sk_rcvbuf value can be changed by other cpus, and KCSAN complains. Add READ_ONCE() annotations to document the lockless nature of these reads. Note that writes over sk_rcvbuf should also use WRITE_ONCE(), but this will be done in separate patches to ease stable backports (if we decide this is relevant for stable trees). BUG: KCSAN: data-race in tcp_add_backlog / tcp_recvmsg write to 0xffff88812ab369f8 of 8 bytes by interrupt on cpu 1: __sk_add_backlog include/net/sock.h:902 [inline] sk_add_backlog include/net/sock.h:933 [inline] tcp_add_backlog+0x45a/0xcc0 net/ipv4/tcp_ipv4.c:1737 tcp_v4_rcv+0x1aba/0x1bf0 net/ipv4/tcp_ipv4.c:1925 ip_protocol_deliver_rcu+0x51/0x470 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:442 [inline] ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5004 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5118 netif_receive_skb_internal+0x59/0x190 net/core/dev.c:5208 napi_skb_finish net/core/dev.c:5671 [inline] napi_gro_receive+0x28f/0x330 net/core/dev.c:5704 receive_buf+0x284/0x30b0 drivers/net/virtio_net.c:1061 virtnet_receive drivers/net/virtio_net.c:1323 [inline] virtnet_poll+0x436/0x7d0 drivers/net/virtio_net.c:1428 napi_poll net/core/dev.c:6352 [inline] net_rx_action+0x3ae/0xa50 net/core/dev.c:6418 read to 0xffff88812ab369f8 of 8 bytes by task 7271 on cpu 0: tcp_recvmsg+0x470/0x1a30 net/ipv4/tcp.c:2047 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838 sock_recvmsg_nosec net/socket.c:871 [inline] sock_recvmsg net/socket.c:889 [inline] sock_recvmsg+0x92/0xb0 net/socket.c:885 sock_read_iter+0x15f/0x1e0 net/socket.c:967 call_read_iter include/linux/fs.h:1864 [inline] new_sync_read+0x389/0x4f0 fs/read_write.c:414 __vfs_read+0xb1/0xc0 fs/read_write.c:427 vfs_read fs/read_write.c:461 [inline] vfs_read+0x143/0x2c0 fs/read_write.c:446 ksys_read+0xd5/0x1b0 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x4c/0x60 fs/read_write.c:595 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 7271 Comm: syz-fuzzer Not tainted 5.3.0+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> 
sk_add_backlog() callers usually read sk->sk_rcvbuf without
owning the socket lock. This means sk_rcvbuf value can
be changed by other cpus, and KCSAN complains.

Add READ_ONCE() annotations to document the lockless nature
of these reads.

Note that writes over sk_rcvbuf should also use WRITE_ONCE(),
but this will be done in separate patches to ease stable
backports (if we decide this is relevant for stable trees).

BUG: KCSAN: data-race in tcp_add_backlog / tcp_recvmsg

write to 0xffff88812ab369f8 of 8 bytes by interrupt on cpu 1:
 __sk_add_backlog include/net/sock.h:902 [inline]
 sk_add_backlog include/net/sock.h:933 [inline]
 tcp_add_backlog+0x45a/0xcc0 net/ipv4/tcp_ipv4.c:1737
 tcp_v4_rcv+0x1aba/0x1bf0 net/ipv4/tcp_ipv4.c:1925
 ip_protocol_deliver_rcu+0x51/0x470 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5004
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5118
 netif_receive_skb_internal+0x59/0x190 net/core/dev.c:5208
 napi_skb_finish net/core/dev.c:5671 [inline]
 napi_gro_receive+0x28f/0x330 net/core/dev.c:5704
 receive_buf+0x284/0x30b0 drivers/net/virtio_net.c:1061
 virtnet_receive drivers/net/virtio_net.c:1323 [inline]
 virtnet_poll+0x436/0x7d0 drivers/net/virtio_net.c:1428
 napi_poll net/core/dev.c:6352 [inline]
 net_rx_action+0x3ae/0xa50 net/core/dev.c:6418

read to 0xffff88812ab369f8 of 8 bytes by task 7271 on cpu 0:
 tcp_recvmsg+0x470/0x1a30 net/ipv4/tcp.c:2047
 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838
 sock_recvmsg_nosec net/socket.c:871 [inline]
 sock_recvmsg net/socket.c:889 [inline]
 sock_recvmsg+0x92/0xb0 net/socket.c:885
 sock_read_iter+0x15f/0x1e0 net/socket.c:967
 call_read_iter include/linux/fs.h:1864 [inline]
 new_sync_read+0x389/0x4f0 fs/read_write.c:414
 __vfs_read+0xb1/0xc0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7271 Comm: syz-fuzzer Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
llc: fix sk_buff refcounting in llc_conn_state_process() 2019-10-08T20:23:05+00:00 Eric Biggers ebiggers@google.com 2019-10-06T21:24:27+00:00 36453c852816f19947ca482a595dffdd2efa4965 If llc_conn_state_process() sees that llc_conn_service() put the skb on a list, it will drop one fewer references to it. This is wrong because the current behavior is that llc_conn_service() never consumes a reference to the skb. The code also makes the number of skb references being dropped conditional on which of ind_prim and cfm_prim are nonzero, yet neither of these affects how many references are *acquired*. So there is extra code that tries to fix this up by sometimes taking another reference. Remove the unnecessary/broken refcounting logic and instead just add an skb_get() before the only two places where an extra reference is actually consumed. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> 
If llc_conn_state_process() sees that llc_conn_service() put the skb on
a list, it will drop one fewer references to it.  This is wrong because
the current behavior is that llc_conn_service() never consumes a
reference to the skb.

The code also makes the number of skb references being dropped
conditional on which of ind_prim and cfm_prim are nonzero, yet neither
of these affects how many references are *acquired*.  So there is extra
code that tries to fix this up by sometimes taking another reference.

Remove the unnecessary/broken refcounting logic and instead just add an
skb_get() before the only two places where an extra reference is
actually consumed.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
llc: fix another potential sk_buff leak in llc_ui_sendmsg() 2019-10-08T20:23:05+00:00 Eric Biggers ebiggers@google.com 2019-10-06T21:24:26+00:00 fc8d5db10cbe1338a52ebc74e7feab9276721774 All callers of llc_conn_state_process() except llc_build_and_send_pkt() (via llc_ui_sendmsg() -> llc_ui_send_data()) assume that it always consumes a reference to the skb. Fix this caller to do the same. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> 
All callers of llc_conn_state_process() except llc_build_and_send_pkt()
(via llc_ui_sendmsg() -> llc_ui_send_data()) assume that it always
consumes a reference to the skb.  Fix this caller to do the same.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
llc: fix sk_buff leak in llc_conn_service() 2019-10-08T20:23:05+00:00 Eric Biggers ebiggers@google.com 2019-10-06T21:24:25+00:00 b74555de21acd791f12c4a1aeaf653dd7ac21133 syzbot reported: BUG: memory leak unreferenced object 0xffff88811eb3de00 (size 224): comm "syz-executor559", pid 7315, jiffies 4294943019 (age 10.300s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 a0 38 24 81 88 ff ff 00 c0 f2 15 81 88 ff ff ..8$............ backtrace: [<000000008d1c66a1>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline] [<000000008d1c66a1>] slab_post_alloc_hook mm/slab.h:439 [inline] [<000000008d1c66a1>] slab_alloc_node mm/slab.c:3269 [inline] [<000000008d1c66a1>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579 [<00000000447d9496>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198 [<000000000cdbf82f>] alloc_skb include/linux/skbuff.h:1058 [inline] [<000000000cdbf82f>] llc_alloc_frame+0x66/0x110 net/llc/llc_sap.c:54 [<000000002418b52e>] llc_conn_ac_send_sabme_cmd_p_set_x+0x2f/0x140 net/llc/llc_c_ac.c:777 [<000000001372ae17>] llc_exec_conn_trans_actions net/llc/llc_conn.c:475 [inline] [<000000001372ae17>] llc_conn_service net/llc/llc_conn.c:400 [inline] [<000000001372ae17>] llc_conn_state_process+0x1ac/0x640 net/llc/llc_conn.c:75 [<00000000f27e53c1>] llc_establish_connection+0x110/0x170 net/llc/llc_if.c:109 [<00000000291b2ca0>] llc_ui_connect+0x10e/0x370 net/llc/af_llc.c:477 [<000000000f9c740b>] __sys_connect+0x11d/0x170 net/socket.c:1840 [...] The bug is that most callers of llc_conn_send_pdu() assume it consumes a reference to the skb, when actually due to commit b85ab56c3f81 ("llc: properly handle dev_queue_xmit() return value") it doesn't. Revert most of that commit, and instead make the few places that need llc_conn_send_pdu() to *not* consume a reference call skb_get() before. Fixes: b85ab56c3f81 ("llc: properly handle dev_queue_xmit() return value") Reported-by: syzbot+6b825a6494a04cc0e3f7@syzkaller.appspotmail.com Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> 
syzbot reported:

    BUG: memory leak
    unreferenced object 0xffff88811eb3de00 (size 224):
       comm "syz-executor559", pid 7315, jiffies 4294943019 (age 10.300s)
       hex dump (first 32 bytes):
         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
         00 a0 38 24 81 88 ff ff 00 c0 f2 15 81 88 ff ff  ..8$............
       backtrace:
         [<000000008d1c66a1>] kmemleak_alloc_recursive  include/linux/kmemleak.h:55 [inline]
         [<000000008d1c66a1>] slab_post_alloc_hook mm/slab.h:439 [inline]
         [<000000008d1c66a1>] slab_alloc_node mm/slab.c:3269 [inline]
         [<000000008d1c66a1>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
         [<00000000447d9496>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
         [<000000000cdbf82f>] alloc_skb include/linux/skbuff.h:1058 [inline]
         [<000000000cdbf82f>] llc_alloc_frame+0x66/0x110 net/llc/llc_sap.c:54
         [<000000002418b52e>] llc_conn_ac_send_sabme_cmd_p_set_x+0x2f/0x140  net/llc/llc_c_ac.c:777
         [<000000001372ae17>] llc_exec_conn_trans_actions net/llc/llc_conn.c:475  [inline]
         [<000000001372ae17>] llc_conn_service net/llc/llc_conn.c:400 [inline]
         [<000000001372ae17>] llc_conn_state_process+0x1ac/0x640  net/llc/llc_conn.c:75
         [<00000000f27e53c1>] llc_establish_connection+0x110/0x170  net/llc/llc_if.c:109
         [<00000000291b2ca0>] llc_ui_connect+0x10e/0x370 net/llc/af_llc.c:477
         [<000000000f9c740b>] __sys_connect+0x11d/0x170 net/socket.c:1840
         [...]

The bug is that most callers of llc_conn_send_pdu() assume it consumes a
reference to the skb, when actually due to commit b85ab56c3f81 ("llc:
properly handle dev_queue_xmit() return value") it doesn't.

Revert most of that commit, and instead make the few places that need
llc_conn_send_pdu() to *not* consume a reference call skb_get() before.

Fixes: b85ab56c3f81 ("llc: properly handle dev_queue_xmit() return value")
Reported-by: syzbot+6b825a6494a04cc0e3f7@syzkaller.appspotmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
llc: fix sk_buff leak in llc_sap_state_process() 2019-10-08T20:23:05+00:00 Eric Biggers ebiggers@google.com 2019-10-06T21:24:24+00:00 c6ee11c39fcc1fb55130748990a8f199e76263b4 syzbot reported: BUG: memory leak unreferenced object 0xffff888116270800 (size 224): comm "syz-executor641", pid 7047, jiffies 4294947360 (age 13.860s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 20 e1 2a 81 88 ff ff 00 40 3d 2a 81 88 ff ff . .*.....@=*.... backtrace: [<000000004d41b4cc>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline] [<000000004d41b4cc>] slab_post_alloc_hook mm/slab.h:439 [inline] [<000000004d41b4cc>] slab_alloc_node mm/slab.c:3269 [inline] [<000000004d41b4cc>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579 [<00000000506a5965>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198 [<000000001ba5a161>] alloc_skb include/linux/skbuff.h:1058 [inline] [<000000001ba5a161>] alloc_skb_with_frags+0x5f/0x250 net/core/skbuff.c:5327 [<0000000047d9c78b>] sock_alloc_send_pskb+0x269/0x2a0 net/core/sock.c:2225 [<000000003828fe54>] sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2242 [<00000000e34d94f9>] llc_ui_sendmsg+0x10a/0x540 net/llc/af_llc.c:933 [<00000000de2de3fb>] sock_sendmsg_nosec net/socket.c:652 [inline] [<00000000de2de3fb>] sock_sendmsg+0x54/0x70 net/socket.c:671 [<000000008fe16e7a>] __sys_sendto+0x148/0x1f0 net/socket.c:1964 [...] The bug is that llc_sap_state_process() always takes an extra reference to the skb, but sometimes neither llc_sap_next_state() nor llc_sap_state_process() itself drops this reference. Fix it by changing llc_sap_next_state() to never consume a reference to the skb, rather than sometimes do so and sometimes not. Then remove the extra skb_get() and kfree_skb() from llc_sap_state_process(). Reported-by: syzbot+6bf095f9becf5efef645@syzkaller.appspotmail.com Reported-by: syzbot+31c16aa4202dace3812e@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> 
syzbot reported:

    BUG: memory leak
    unreferenced object 0xffff888116270800 (size 224):
       comm "syz-executor641", pid 7047, jiffies 4294947360 (age 13.860s)
       hex dump (first 32 bytes):
         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
         00 20 e1 2a 81 88 ff ff 00 40 3d 2a 81 88 ff ff  . .*.....@=*....
       backtrace:
         [<000000004d41b4cc>] kmemleak_alloc_recursive  include/linux/kmemleak.h:55 [inline]
         [<000000004d41b4cc>] slab_post_alloc_hook mm/slab.h:439 [inline]
         [<000000004d41b4cc>] slab_alloc_node mm/slab.c:3269 [inline]
         [<000000004d41b4cc>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
         [<00000000506a5965>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
         [<000000001ba5a161>] alloc_skb include/linux/skbuff.h:1058 [inline]
         [<000000001ba5a161>] alloc_skb_with_frags+0x5f/0x250  net/core/skbuff.c:5327
         [<0000000047d9c78b>] sock_alloc_send_pskb+0x269/0x2a0  net/core/sock.c:2225
         [<000000003828fe54>] sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2242
         [<00000000e34d94f9>] llc_ui_sendmsg+0x10a/0x540 net/llc/af_llc.c:933
         [<00000000de2de3fb>] sock_sendmsg_nosec net/socket.c:652 [inline]
         [<00000000de2de3fb>] sock_sendmsg+0x54/0x70 net/socket.c:671
         [<000000008fe16e7a>] __sys_sendto+0x148/0x1f0 net/socket.c:1964
	 [...]

The bug is that llc_sap_state_process() always takes an extra reference
to the skb, but sometimes neither llc_sap_next_state() nor
llc_sap_state_process() itself drops this reference.

Fix it by changing llc_sap_next_state() to never consume a reference to
the skb, rather than sometimes do so and sometimes not.  Then remove the
extra skb_get() and kfree_skb() from llc_sap_state_process().

Reported-by: syzbot+6bf095f9becf5efef645@syzkaller.appspotmail.com
Reported-by: syzbot+31c16aa4202dace3812e@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 281 2019-06-05T15:36:36+00:00 Thomas Gleixner tglx@linutronix.de 2019-05-29T14:17:55+00:00 0e9facca1b882b4034acc8f38a4f2ab6797f270a Based on 1 normalized pattern(s): this program can be redistributed or modified under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed without any warranty or implied warranty of merchantability or fitness for a particular purpose see the gnu general public license version 2 for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 1 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141900.551133917@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Based on 1 normalized pattern(s):

  this program can be redistributed or modified under the terms of the
  gnu general public license version 2 as published by the free
  software foundation this program is distributed without any warranty
  or implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license version 2 for more
  details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 1 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141900.551133917@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
llc: fix skb leak in llc_build_and_send_ui_pkt() 2019-05-29T00:25:23+00:00 Eric Dumazet edumazet@google.com 2019-05-28T00:35:52+00:00 8fb44d60d4142cd2a440620cd291d346e23c131e If llc_mac_hdr_init() returns an error, we must drop the skb since no llc_build_and_send_ui_pkt() caller will take care of this. BUG: memory leak unreferenced object 0xffff8881202b6800 (size 2048): comm "syz-executor907", pid 7074, jiffies 4294943781 (age 8.590s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 1a 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace: [<00000000e25b5abe>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline] [<00000000e25b5abe>] slab_post_alloc_hook mm/slab.h:439 [inline] [<00000000e25b5abe>] slab_alloc mm/slab.c:3326 [inline] [<00000000e25b5abe>] __do_kmalloc mm/slab.c:3658 [inline] [<00000000e25b5abe>] __kmalloc+0x161/0x2c0 mm/slab.c:3669 [<00000000a1ae188a>] kmalloc include/linux/slab.h:552 [inline] [<00000000a1ae188a>] sk_prot_alloc+0xd6/0x170 net/core/sock.c:1608 [<00000000ded25bbe>] sk_alloc+0x35/0x2f0 net/core/sock.c:1662 [<000000002ecae075>] llc_sk_alloc+0x35/0x170 net/llc/llc_conn.c:950 [<00000000551f7c47>] llc_ui_create+0x7b/0x140 net/llc/af_llc.c:173 [<0000000029027f0e>] __sock_create+0x164/0x250 net/socket.c:1430 [<000000008bdec225>] sock_create net/socket.c:1481 [inline] [<000000008bdec225>] __sys_socket+0x69/0x110 net/socket.c:1523 [<00000000b6439228>] __do_sys_socket net/socket.c:1532 [inline] [<00000000b6439228>] __se_sys_socket net/socket.c:1530 [inline] [<00000000b6439228>] __x64_sys_socket+0x1e/0x30 net/socket.c:1530 [<00000000cec820c1>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301 [<000000000c32554f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 BUG: memory leak unreferenced object 0xffff88811d750d00 (size 224): comm "syz-executor907", pid 7074, jiffies 4294943781 (age 8.600s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 f0 0c 24 81 88 ff ff 00 68 2b 20 81 88 ff ff ...$.....h+ .... backtrace: [<0000000053026172>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline] [<0000000053026172>] slab_post_alloc_hook mm/slab.h:439 [inline] [<0000000053026172>] slab_alloc_node mm/slab.c:3269 [inline] [<0000000053026172>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579 [<00000000fa8f3c30>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198 [<00000000d96fdafb>] alloc_skb include/linux/skbuff.h:1058 [inline] [<00000000d96fdafb>] alloc_skb_with_frags+0x5f/0x250 net/core/skbuff.c:5327 [<000000000a34a2e7>] sock_alloc_send_pskb+0x269/0x2a0 net/core/sock.c:2225 [<00000000ee39999b>] sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2242 [<00000000e034d810>] llc_ui_sendmsg+0x10a/0x540 net/llc/af_llc.c:933 [<00000000c0bc8445>] sock_sendmsg_nosec net/socket.c:652 [inline] [<00000000c0bc8445>] sock_sendmsg+0x54/0x70 net/socket.c:671 [<000000003b687167>] __sys_sendto+0x148/0x1f0 net/socket.c:1964 [<00000000922d78d9>] __do_sys_sendto net/socket.c:1976 [inline] [<00000000922d78d9>] __se_sys_sendto net/socket.c:1972 [inline] [<00000000922d78d9>] __x64_sys_sendto+0x2a/0x30 net/socket.c:1972 [<00000000cec820c1>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301 [<000000000c32554f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
If llc_mac_hdr_init() returns an error, we must drop the skb
since no llc_build_and_send_ui_pkt() caller will take care of this.

BUG: memory leak
unreferenced object 0xffff8881202b6800 (size 2048):
  comm "syz-executor907", pid 7074, jiffies 4294943781 (age 8.590s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    1a 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............
  backtrace:
    [<00000000e25b5abe>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
    [<00000000e25b5abe>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<00000000e25b5abe>] slab_alloc mm/slab.c:3326 [inline]
    [<00000000e25b5abe>] __do_kmalloc mm/slab.c:3658 [inline]
    [<00000000e25b5abe>] __kmalloc+0x161/0x2c0 mm/slab.c:3669
    [<00000000a1ae188a>] kmalloc include/linux/slab.h:552 [inline]
    [<00000000a1ae188a>] sk_prot_alloc+0xd6/0x170 net/core/sock.c:1608
    [<00000000ded25bbe>] sk_alloc+0x35/0x2f0 net/core/sock.c:1662
    [<000000002ecae075>] llc_sk_alloc+0x35/0x170 net/llc/llc_conn.c:950
    [<00000000551f7c47>] llc_ui_create+0x7b/0x140 net/llc/af_llc.c:173
    [<0000000029027f0e>] __sock_create+0x164/0x250 net/socket.c:1430
    [<000000008bdec225>] sock_create net/socket.c:1481 [inline]
    [<000000008bdec225>] __sys_socket+0x69/0x110 net/socket.c:1523
    [<00000000b6439228>] __do_sys_socket net/socket.c:1532 [inline]
    [<00000000b6439228>] __se_sys_socket net/socket.c:1530 [inline]
    [<00000000b6439228>] __x64_sys_socket+0x1e/0x30 net/socket.c:1530
    [<00000000cec820c1>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301
    [<000000000c32554f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff88811d750d00 (size 224):
  comm "syz-executor907", pid 7074, jiffies 4294943781 (age 8.600s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 f0 0c 24 81 88 ff ff 00 68 2b 20 81 88 ff ff  ...$.....h+ ....
  backtrace:
    [<0000000053026172>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
    [<0000000053026172>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<0000000053026172>] slab_alloc_node mm/slab.c:3269 [inline]
    [<0000000053026172>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
    [<00000000fa8f3c30>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
    [<00000000d96fdafb>] alloc_skb include/linux/skbuff.h:1058 [inline]
    [<00000000d96fdafb>] alloc_skb_with_frags+0x5f/0x250 net/core/skbuff.c:5327
    [<000000000a34a2e7>] sock_alloc_send_pskb+0x269/0x2a0 net/core/sock.c:2225
    [<00000000ee39999b>] sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2242
    [<00000000e034d810>] llc_ui_sendmsg+0x10a/0x540 net/llc/af_llc.c:933
    [<00000000c0bc8445>] sock_sendmsg_nosec net/socket.c:652 [inline]
    [<00000000c0bc8445>] sock_sendmsg+0x54/0x70 net/socket.c:671
    [<000000003b687167>] __sys_sendto+0x148/0x1f0 net/socket.c:1964
    [<00000000922d78d9>] __do_sys_sendto net/socket.c:1976 [inline]
    [<00000000922d78d9>] __se_sys_sendto net/socket.c:1972 [inline]
    [<00000000922d78d9>] __x64_sys_sendto+0x2a/0x30 net/socket.c:1972
    [<00000000cec820c1>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301
    [<000000000c32554f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21T08:50:46+00:00 Thomas Gleixner tglx@linutronix.de 2019-05-19T12:07:45+00:00 ec8f24b7faaf3d4799a7c3f4c1b87f6b02778ad1 Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
llc: Check address length before reading address field 2019-04-12T17:25:03+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2019-04-12T10:55:14+00:00 c68e747d0a98f44a4e49071940a692fa83630e47 KMSAN will complain if valid address length passed to bind() is shorter than sizeof(struct sockaddr_llc) bytes. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: David S. Miller <davem@davemloft.net> 
KMSAN will complain if valid address length passed to bind() is shorter
than sizeof(struct sockaddr_llc) bytes.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
llc: do not use sk_eat_skb() 2018-10-23T02:59:20+00:00 Eric Dumazet edumazet@google.com 2018-10-22T16:24:27+00:00 604d415e2bd642b7e02c80e719e0396b9d4a77a6 syzkaller triggered a use-after-free [1], caused by a combination of skb_get() in llc_conn_state_process() and usage of sk_eat_skb() sk_eat_skb() is assuming the skb about to be freed is only used by the current thread. TCP/DCCP stacks enforce this because current thread holds the socket lock. llc_conn_state_process() wants to make sure skb does not disappear, and holds a reference on the skb it manipulates. But as soon as this skb is added to socket receive queue, another thread can consume it. This means that llc must use regular skb_unlink() and kfree_skb() so that both producer and consumer can safely work on the same skb. [1] BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43 [inline] BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:967 [inline] BUG: KASAN: use-after-free in kfree_skb+0xb7/0x580 net/core/skbuff.c:655 Read of size 4 at addr ffff8801d1f6fba4 by task ksoftirqd/1/18 CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.19.0-rc8+ #295 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+0x1c4/0x2b6 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] refcount_read include/linux/refcount.h:43 [inline] skb_unref include/linux/skbuff.h:967 [inline] kfree_skb+0xb7/0x580 net/core/skbuff.c:655 llc_sap_state_process+0x9b/0x550 net/llc/llc_sap.c:224 llc_sap_rcv+0x156/0x1f0 net/llc/llc_sap.c:297 llc_sap_handler+0x65e/0xf80 net/llc/llc_sap.c:438 llc_rcv+0x79e/0xe20 net/llc/llc_input.c:208 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023 process_backlog+0x218/0x6f0 net/core/dev.c:5829 napi_poll net/core/dev.c:6249 [inline] net_rx_action+0x7c5/0x1950 net/core/dev.c:6315 __do_softirq+0x30c/0xb03 kernel/softirq.c:292 run_ksoftirqd+0x94/0x100 kernel/softirq.c:653 smpboot_thread_fn+0x68b/0xa00 kernel/smpboot.c:164 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 Allocated by task 18: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc_node+0x144/0x730 mm/slab.c:3644 __alloc_skb+0x119/0x770 net/core/skbuff.c:193 alloc_skb include/linux/skbuff.h:995 [inline] llc_alloc_frame+0xbc/0x370 net/llc/llc_sap.c:54 llc_station_ac_send_xid_r net/llc/llc_station.c:52 [inline] llc_station_rcv+0x1dc/0x1420 net/llc/llc_station.c:111 llc_rcv+0xc32/0xe20 net/llc/llc_input.c:220 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023 process_backlog+0x218/0x6f0 net/core/dev.c:5829 napi_poll net/core/dev.c:6249 [inline] net_rx_action+0x7c5/0x1950 net/core/dev.c:6315 __do_softirq+0x30c/0xb03 kernel/softirq.c:292 Freed by task 16383: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3756 kfree_skbmem+0x154/0x230 net/core/skbuff.c:582 __kfree_skb+0x1d/0x20 net/core/skbuff.c:642 sk_eat_skb include/net/sock.h:2366 [inline] llc_ui_recvmsg+0xec2/0x1610 net/llc/af_llc.c:882 sock_recvmsg_nosec net/socket.c:794 [inline] sock_recvmsg+0xd0/0x110 net/socket.c:801 ___sys_recvmsg+0x2b6/0x680 net/socket.c:2278 __sys_recvmmsg+0x303/0xb90 net/socket.c:2390 do_sys_recvmmsg+0x181/0x1a0 net/socket.c:2466 __do_sys_recvmmsg net/socket.c:2484 [inline] __se_sys_recvmmsg net/socket.c:2480 [inline] __x64_sys_recvmmsg+0xbe/0x150 net/socket.c:2480 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801d1f6fac0 which belongs to the cache skbuff_head_cache of size 232 The buggy address is located 228 bytes inside of 232-byte region [ffff8801d1f6fac0, ffff8801d1f6fba8) The buggy address belongs to the page: page:ffffea000747dbc0 count:1 mapcount:0 mapping:ffff8801d9be7680 index:0xffff8801d1f6fe80 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0007346e88 ffffea000705b108 ffff8801d9be7680 raw: ffff8801d1f6fe80 ffff8801d1f6f0c0 000000010000000b 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d1f6fa80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8801d1f6fb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801d1f6fb80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc ^ ffff8801d1f6fc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d1f6fc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
syzkaller triggered a use-after-free [1], caused by a combination of
skb_get() in llc_conn_state_process() and usage of sk_eat_skb()

sk_eat_skb() is assuming the skb about to be freed is only used by
the current thread. TCP/DCCP stacks enforce this because current
thread holds the socket lock.

llc_conn_state_process() wants to make sure skb does not disappear,
and holds a reference on the skb it manipulates. But as soon as this
skb is added to socket receive queue, another thread can consume it.

This means that llc must use regular skb_unlink() and kfree_skb()
so that both producer and consumer can safely work on the same skb.

[1]
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43 [inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:967 [inline]
BUG: KASAN: use-after-free in kfree_skb+0xb7/0x580 net/core/skbuff.c:655
Read of size 4 at addr ffff8801d1f6fba4 by task ksoftirqd/1/18

CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.19.0-rc8+ #295
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+0x1c4/0x2b6 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 refcount_read include/linux/refcount.h:43 [inline]
 skb_unref include/linux/skbuff.h:967 [inline]
 kfree_skb+0xb7/0x580 net/core/skbuff.c:655
 llc_sap_state_process+0x9b/0x550 net/llc/llc_sap.c:224
 llc_sap_rcv+0x156/0x1f0 net/llc/llc_sap.c:297
 llc_sap_handler+0x65e/0xf80 net/llc/llc_sap.c:438
 llc_rcv+0x79e/0xe20 net/llc/llc_input.c:208
 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913
 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023
 process_backlog+0x218/0x6f0 net/core/dev.c:5829
 napi_poll net/core/dev.c:6249 [inline]
 net_rx_action+0x7c5/0x1950 net/core/dev.c:6315
 __do_softirq+0x30c/0xb03 kernel/softirq.c:292
 run_ksoftirqd+0x94/0x100 kernel/softirq.c:653
 smpboot_thread_fn+0x68b/0xa00 kernel/smpboot.c:164
 kthread+0x35a/0x420 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413

Allocated by task 18:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc_node+0x144/0x730 mm/slab.c:3644
 __alloc_skb+0x119/0x770 net/core/skbuff.c:193
 alloc_skb include/linux/skbuff.h:995 [inline]
 llc_alloc_frame+0xbc/0x370 net/llc/llc_sap.c:54
 llc_station_ac_send_xid_r net/llc/llc_station.c:52 [inline]
 llc_station_rcv+0x1dc/0x1420 net/llc/llc_station.c:111
 llc_rcv+0xc32/0xe20 net/llc/llc_input.c:220
 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913
 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023
 process_backlog+0x218/0x6f0 net/core/dev.c:5829
 napi_poll net/core/dev.c:6249 [inline]
 net_rx_action+0x7c5/0x1950 net/core/dev.c:6315
 __do_softirq+0x30c/0xb03 kernel/softirq.c:292

Freed by task 16383:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x83/0x290 mm/slab.c:3756
 kfree_skbmem+0x154/0x230 net/core/skbuff.c:582
 __kfree_skb+0x1d/0x20 net/core/skbuff.c:642
 sk_eat_skb include/net/sock.h:2366 [inline]
 llc_ui_recvmsg+0xec2/0x1610 net/llc/af_llc.c:882
 sock_recvmsg_nosec net/socket.c:794 [inline]
 sock_recvmsg+0xd0/0x110 net/socket.c:801
 ___sys_recvmsg+0x2b6/0x680 net/socket.c:2278
 __sys_recvmmsg+0x303/0xb90 net/socket.c:2390
 do_sys_recvmmsg+0x181/0x1a0 net/socket.c:2466
 __do_sys_recvmmsg net/socket.c:2484 [inline]
 __se_sys_recvmmsg net/socket.c:2480 [inline]
 __x64_sys_recvmmsg+0xbe/0x150 net/socket.c:2480
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d1f6fac0
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of
 232-byte region [ffff8801d1f6fac0, ffff8801d1f6fba8)
The buggy address belongs to the page:
page:ffffea000747dbc0 count:1 mapcount:0 mapping:ffff8801d9be7680 index:0xffff8801d1f6fe80
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0007346e88 ffffea000705b108 ffff8801d9be7680
raw: ffff8801d1f6fe80 ffff8801d1f6f0c0 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d1f6fa80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801d1f6fb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801d1f6fb80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
                               ^
 ffff8801d1f6fc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d1f6fc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>