linux.git/include/net, branch v4.13 Linux kernel source tree ipv6: fix sparse warning on rt6i_node 2017-08-28T22:34:40+00:00 Wei Wang weiwan@google.com 2017-08-25T22:03:10+00:00 4e587ea71bf924f7dac621f1351653bd41e446cb Commit c5cff8561d2d adds rcu grace period before freeing fib6_node. This generates a new sparse warning on rt->rt6i_node related code: net/ipv6/route.c:1394:30: error: incompatible types in comparison expression (different address spaces) ./include/net/ip6_fib.h:187:14: error: incompatible types in comparison expression (different address spaces) This commit adds "__rcu" tag for rt6i_node and makes sure corresponding rcu API is used for it. After this fix, sparse no longer generates the above warning. Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node") Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Commit c5cff8561d2d adds rcu grace period before freeing fib6_node. This
generates a new sparse warning on rt->rt6i_node related code:
  net/ipv6/route.c:1394:30: error: incompatible types in comparison
  expression (different address spaces)
  ./include/net/ip6_fib.h:187:14: error: incompatible types in comparison
  expression (different address spaces)

This commit adds "__rcu" tag for rt6i_node and makes sure corresponding
rcu API is used for it.
After this fix, sparse no longer generates the above warning.

Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node")
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
udp6: set rx_dst_cookie on rx_dst updates 2017-08-26T03:09:13+00:00 Paolo Abeni pabeni@redhat.com 2017-08-25T12:31:01+00:00 64f0f5d18a47c703c85576375cc010e83dac6a48 Currently, in the udp6 code, the dst cookie is not initialized/updated concurrently with the RX dst used by early demux. As a result, the dst_check() in the early_demux path always fails, the rx dst cache is always invalidated, and we can't really leverage significant gain from the demux lookup. Fix it adding udp6 specific variant of sk_rx_dst_set() and use it to set the dst cookie when the dst entry is really changed. The issue is there since the introduction of early demux for ipv6. Fixes: 5425077d73e0 ("net: ipv6: Add early demux handler for UDP unicast") Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Currently, in the udp6 code, the dst cookie is not initialized/updated
concurrently with the RX dst used by early demux.

As a result, the dst_check() in the early_demux path always fails,
the rx dst cache is always invalidated, and we can't really
leverage significant gain from the demux lookup.

Fix it adding udp6 specific variant of sk_rx_dst_set() and use it
to set the dst cookie when the dst entry is really changed.

The issue is there since the introduction of early demux for ipv6.

Fixes: 5425077d73e0 ("net: ipv6: Add early demux handler for UDP unicast")
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: fix refcnt leak with ebpf congestion control 2017-08-26T00:16:27+00:00 Sabrina Dubroca sd@queasysnail.net 2017-08-25T11:10:12+00:00 ebfa00c5745660fe7f0a91eea88d4dff658486c4 There are a few bugs around refcnt handling in the new BPF congestion control setsockopt: - The new ca is assigned to icsk->icsk_ca_ops even in the case where we cannot get a reference on it. This would lead to a use after free, since that ca is going away soon. - Changing the congestion control case doesn't release the refcnt on the previous ca. - In the reinit case, we first leak a reference on the old ca, then we call tcp_reinit_congestion_control on the ca that we have just assigned, leading to deinitializing the wrong ca (->release of the new ca on the old ca's data) and releasing the refcount on the ca that we actually want to use. This is visible by building (for example) BIC as a module and setting net.ipv4.tcp_congestion_control=bic, and using tcp_cong_kern.c from samples/bpf. This patch fixes the refcount issues, and moves reinit back into tcp core to avoid passing a ca pointer back to BPF. Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Acked-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
There are a few bugs around refcnt handling in the new BPF congestion
control setsockopt:

 - The new ca is assigned to icsk->icsk_ca_ops even in the case where we
   cannot get a reference on it. This would lead to a use after free,
   since that ca is going away soon.

 - Changing the congestion control case doesn't release the refcnt on
   the previous ca.

 - In the reinit case, we first leak a reference on the old ca, then we
   call tcp_reinit_congestion_control on the ca that we have just
   assigned, leading to deinitializing the wrong ca (->release of the
   new ca on the old ca's data) and releasing the refcount on the ca
   that we actually want to use.

This is visible by building (for example) BIC as a module and setting
net.ipv4.tcp_congestion_control=bic, and using tcp_cong_kern.c from
samples/bpf.

This patch fixes the refcount issues, and moves reinit back into tcp
core to avoid passing a ca pointer back to BPF.

Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net_sched: fix a refcount_t issue with noop_qdisc 2017-08-25T04:28:24+00:00 Eric Dumazet edumazet@google.com 2017-08-25T04:12:28+00:00 551143d8d954fe398324a5caa276f518466c428b syzkaller reported a refcount_t warning [1] Issue here is that noop_qdisc refcnt was never really considered as a true refcount, since qdisc_destroy() found TCQ_F_BUILTIN set : if (qdisc->flags & TCQ_F_BUILTIN || !refcount_dec_and_test(&qdisc->refcnt))) return; Meaning that all atomic_inc() we did on noop_qdisc.refcnt were not really needed, but harmless until refcount_t came. To fix this problem, we simply need to not increment noop_qdisc.refcnt, since we never decrement it. [1] refcount_t: increment on 0; use-after-free. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 21754 at lib/refcount.c:152 refcount_inc+0x47/0x50 lib/refcount.c:152 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 21754 Comm: syz-executor7 Not tainted 4.13.0-rc6+ #20 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 panic+0x1e4/0x417 kernel/panic.c:180 __warn+0x1c4/0x1d9 kernel/panic.c:541 report_bug+0x211/0x2d0 lib/bug.c:183 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:190 do_trap_no_signal arch/x86/kernel/traps.c:224 [inline] do_trap+0x260/0x390 arch/x86/kernel/traps.c:273 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:310 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:323 invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:846 RIP: 0010:refcount_inc+0x47/0x50 lib/refcount.c:152 RSP: 0018:ffff8801c43477a0 EFLAGS: 00010282 RAX: 000000000000002b RBX: ffffffff86093c14 RCX: 0000000000000000 RDX: 000000000000002b RSI: ffffffff8159314e RDI: ffffed0038868ee8 RBP: ffff8801c43477a8 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff86093ac0 R13: 0000000000000001 R14: ffff8801d0f3bac0 R15: dffffc0000000000 attach_default_qdiscs net/sched/sch_generic.c:792 [inline] dev_activate+0x7d3/0xaa0 net/sched/sch_generic.c:833 __dev_open+0x227/0x330 net/core/dev.c:1380 __dev_change_flags+0x695/0x990 net/core/dev.c:6726 dev_change_flags+0x88/0x140 net/core/dev.c:6792 dev_ifsioc+0x5a6/0x930 net/core/dev_ioctl.c:256 dev_ioctl+0x2bc/0xf90 net/core/dev_ioctl.c:554 sock_do_ioctl+0x94/0xb0 net/socket.c:968 sock_ioctl+0x2c2/0x440 net/socket.c:1058 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 Fixes: 7b9364050246 ("net, sched: convert Qdisc.refcnt from atomic_t to refcount_t") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Reshetova, Elena <elena.reshetova@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
syzkaller reported a refcount_t warning [1]

Issue here is that noop_qdisc refcnt was never really considered as
a true refcount, since qdisc_destroy() found TCQ_F_BUILTIN set :

if (qdisc->flags & TCQ_F_BUILTIN ||
    !refcount_dec_and_test(&qdisc->refcnt)))
	return;

Meaning that all atomic_inc() we did on noop_qdisc.refcnt were not
really needed, but harmless until refcount_t came.

To fix this problem, we simply need to not increment noop_qdisc.refcnt,
since we never decrement it.

[1]
refcount_t: increment on 0; use-after-free.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 21754 at lib/refcount.c:152 refcount_inc+0x47/0x50 lib/refcount.c:152
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 21754 Comm: syz-executor7 Not tainted 4.13.0-rc6+ #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x417 kernel/panic.c:180
 __warn+0x1c4/0x1d9 kernel/panic.c:541
 report_bug+0x211/0x2d0 lib/bug.c:183
 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:190
 do_trap_no_signal arch/x86/kernel/traps.c:224 [inline]
 do_trap+0x260/0x390 arch/x86/kernel/traps.c:273
 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:310
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:323
 invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:846
RIP: 0010:refcount_inc+0x47/0x50 lib/refcount.c:152
RSP: 0018:ffff8801c43477a0 EFLAGS: 00010282
RAX: 000000000000002b RBX: ffffffff86093c14 RCX: 0000000000000000
RDX: 000000000000002b RSI: ffffffff8159314e RDI: ffffed0038868ee8
RBP: ffff8801c43477a8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff86093ac0
R13: 0000000000000001 R14: ffff8801d0f3bac0 R15: dffffc0000000000
 attach_default_qdiscs net/sched/sch_generic.c:792 [inline]
 dev_activate+0x7d3/0xaa0 net/sched/sch_generic.c:833
 __dev_open+0x227/0x330 net/core/dev.c:1380
 __dev_change_flags+0x695/0x990 net/core/dev.c:6726
 dev_change_flags+0x88/0x140 net/core/dev.c:6792
 dev_ifsioc+0x5a6/0x930 net/core/dev_ioctl.c:256
 dev_ioctl+0x2bc/0xf90 net/core/dev_ioctl.c:554
 sock_do_ioctl+0x94/0xb0 net/socket.c:968
 sock_ioctl+0x2c2/0x440 net/socket.c:1058
 vfs_ioctl fs/ioctl.c:45 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691

Fixes: 7b9364050246 ("net, sched: convert Qdisc.refcnt from atomic_t to refcount_t")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Reshetova, Elena <elena.reshetova@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv6: add rcu grace period before freeing fib6_node 2017-08-22T18:03:19+00:00 Wei Wang weiwan@google.com 2017-08-21T16:47:10+00:00 c5cff8561d2d0006e972bd114afd51f082fee77c We currently keep rt->rt6i_node pointing to the fib6_node for the route. And some functions make use of this pointer to dereference the fib6_node from rt structure, e.g. rt6_check(). However, as there is neither refcount nor rcu taken when dereferencing rt->rt6i_node, it could potentially cause crashes as rt->rt6i_node could be set to NULL by other CPUs when doing a route deletion. This patch introduces an rcu grace period before freeing fib6_node and makes sure the functions that dereference it takes rcu_read_lock(). Note: there is no "Fixes" tag because this bug was there in a very early stage. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We currently keep rt->rt6i_node pointing to the fib6_node for the route.
And some functions make use of this pointer to dereference the fib6_node
from rt structure, e.g. rt6_check(). However, as there is neither
refcount nor rcu taken when dereferencing rt->rt6i_node, it could
potentially cause crashes as rt->rt6i_node could be set to NULL by other
CPUs when doing a route deletion.
This patch introduces an rcu grace period before freeing fib6_node and
makes sure the functions that dereference it takes rcu_read_lock().

Note: there is no "Fixes" tag because this bug was there in a very
early stage.

Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net_sched: fix order of queue length updates in qdisc_replace() 2017-08-21T03:02:00+00:00 Konstantin Khlebnikov khlebnikov@yandex-team.ru 2017-08-19T12:37:07+00:00 68a66d149a8c78ec6720f268597302883e48e9fa This important to call qdisc_tree_reduce_backlog() after changing queue length. Parent qdisc should deactivate class in ->qlen_notify() called from qdisc_tree_reduce_backlog() but this happens only if qdisc->q.qlen in zero. Missed class deactivations leads to crashes/warnings at picking packets from empty qdisc and corrupting state at reactivating this class in future. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Fixes: 86a7996cc8a0 ("net_sched: introduce qdisc_replace() helper") Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This important to call qdisc_tree_reduce_backlog() after changing queue
length. Parent qdisc should deactivate class in ->qlen_notify() called from
qdisc_tree_reduce_backlog() but this happens only if qdisc->q.qlen in zero.

Missed class deactivations leads to crashes/warnings at picking packets
from empty qdisc and corrupting state at reactivating this class in future.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 86a7996cc8a0 ("net_sched: introduce qdisc_replace() helper")
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
datagram: When peeking datagrams with offset < 0 don't skip empty skbs 2017-08-18T22:12:54+00:00 Matthew Dawson matthew@mjdsystems.ca 2017-08-18T19:04:54+00:00 a0917e0bc6efc05834c0c1eafebd579a9c75e6e9 Due to commit e6afc8ace6dd5cef5e812f26c72579da8806f5ac ("udp: remove headers from UDP packets before queueing"), when udp packets are being peeked the requested extra offset is always 0 as there is no need to skip the udp header. However, when the offset is 0 and the next skb is of length 0, it is only returned once. The behaviour can be seen with the following python script: from socket import *; f=socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, 0); g=socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, 0); f.bind(('::', 0)); addr=('::1', f.getsockname()[1]); g.sendto(b'', addr) g.sendto(b'b', addr) print(f.recvfrom(10, MSG_PEEK)); print(f.recvfrom(10, MSG_PEEK)); Where the expected output should be the empty string twice. Instead, make sk_peek_offset return negative values, and pass those values to __skb_try_recv_datagram/__skb_try_recv_from_queue. If the passed offset to __skb_try_recv_from_queue is negative, the checked skb is never skipped. __skb_try_recv_from_queue will then ensure the offset is reset back to 0 if a peek is requested without an offset, unless no packets are found. Also simplify the if condition in __skb_try_recv_from_queue. If _off is greater then 0, and off is greater then or equal to skb->len, then (_off || skb->len) must always be true assuming skb->len >= 0 is always true. Also remove a redundant check around a call to sk_peek_offset in af_unix.c, as it double checked if MSG_PEEK was set in the flags. V2: - Moved the negative fixup into __skb_try_recv_from_queue, and remove now redundant checks - Fix peeking in udp{,v6}_recvmsg to report the right value when the offset is 0 V3: - Marked new branch in __skb_try_recv_from_queue as unlikely. Signed-off-by: Matthew Dawson <matthew@mjdsystems.ca> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Due to commit e6afc8ace6dd5cef5e812f26c72579da8806f5ac ("udp: remove
headers from UDP packets before queueing"), when udp packets are being
peeked the requested extra offset is always 0 as there is no need to skip
the udp header.  However, when the offset is 0 and the next skb is
of length 0, it is only returned once.  The behaviour can be seen with
the following python script:

from socket import *;
f=socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, 0);
g=socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, 0);
f.bind(('::', 0));
addr=('::1', f.getsockname()[1]);
g.sendto(b'', addr)
g.sendto(b'b', addr)
print(f.recvfrom(10, MSG_PEEK));
print(f.recvfrom(10, MSG_PEEK));

Where the expected output should be the empty string twice.

Instead, make sk_peek_offset return negative values, and pass those values
to __skb_try_recv_datagram/__skb_try_recv_from_queue.  If the passed offset
to __skb_try_recv_from_queue is negative, the checked skb is never skipped.
__skb_try_recv_from_queue will then ensure the offset is reset back to 0
if a peek is requested without an offset, unless no packets are found.

Also simplify the if condition in __skb_try_recv_from_queue.  If _off is
greater then 0, and off is greater then or equal to skb->len, then
(_off || skb->len) must always be true assuming skb->len >= 0 is always
true.

Also remove a redundant check around a call to sk_peek_offset in af_unix.c,
as it double checked if MSG_PEEK was set in the flags.

V2:
 - Moved the negative fixup into __skb_try_recv_from_queue, and remove now
redundant checks
 - Fix peeking in udp{,v6}_recvmsg to report the right value when the
offset is 0

V3:
 - Marked new branch in __skb_try_recv_from_queue as unlikely.

Signed-off-by: Matthew Dawson <matthew@mjdsystems.ca>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: better IP_MAX_MTU enforcement 2017-08-16T23:28:47+00:00 Eric Dumazet edumazet@google.com 2017-08-16T18:09:12+00:00 c780a049f9bf442314335372c9abc4548bfe3e44 While working on yet another syzkaller report, I found that our IP_MAX_MTU enforcements were not properly done. gcc seems to reload dev->mtu for min(dev->mtu, IP_MAX_MTU), and final result can be bigger than IP_MAX_MTU :/ This is a problem because device mtu can be changed on other cpus or threads. While this patch does not fix the issue I am working on, it is probably worth addressing it. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
While working on yet another syzkaller report, I found
that our IP_MAX_MTU enforcements were not properly done.

gcc seems to reload dev->mtu for min(dev->mtu, IP_MAX_MTU), and
final result can be bigger than IP_MAX_MTU :/

This is a problem because device mtu can be changed on other cpus or
threads.

While this patch does not fix the issue I am working on, it is
probably worth addressing it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv6: fix NULL dereference in ip6_route_dev_notify() 2017-08-16T00:06:34+00:00 Eric Dumazet edumazet@google.com 2017-08-15T11:09:51+00:00 12d94a804946af291e24b80fc53ec86264765781 Based on a syzkaller report [1], I found that a per cpu allocation failure in snmp6_alloc_dev() would then lead to NULL dereference in ip6_route_dev_notify(). It seems this is a very old bug, thus no Fixes tag in this submission. Let's add in6_dev_put_clear() helper, as we will probably use it elsewhere (once available/present in net-next) [1] kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 17294 Comm: syz-executor6 Not tainted 4.13.0-rc2+ #10 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff88019f456680 task.stack: ffff8801c6e58000 RIP: 0010:__read_once_size include/linux/compiler.h:250 [inline] RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:26 [inline] RIP: 0010:refcount_sub_and_test+0x7d/0x1b0 lib/refcount.c:178 RSP: 0018:ffff8801c6e5f1b0 EFLAGS: 00010202 RAX: 0000000000000037 RBX: dffffc0000000000 RCX: ffffc90005d25000 RDX: ffff8801c6e5f218 RSI: ffffffff82342bbf RDI: 0000000000000001 RBP: ffff8801c6e5f240 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff10038dcbe37 R13: 0000000000000006 R14: 0000000000000001 R15: 00000000000001b8 FS: 00007f21e0429700(0000) GS:ffff8801dc100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001ddbc22000 CR3: 00000001d632b000 CR4: 00000000001426e0 DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: refcount_dec_and_test+0x1a/0x20 lib/refcount.c:211 in6_dev_put include/net/addrconf.h:335 [inline] ip6_route_dev_notify+0x1c9/0x4a0 net/ipv6/route.c:3732 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1678 call_netdevice_notifiers net/core/dev.c:1694 [inline] rollback_registered_many+0x91c/0xe80 net/core/dev.c:7107 rollback_registered+0x1be/0x3c0 net/core/dev.c:7149 register_netdevice+0xbcd/0xee0 net/core/dev.c:7587 register_netdev+0x1a/0x30 net/core/dev.c:7669 loopback_net_init+0x76/0x160 drivers/net/loopback.c:214 ops_init+0x10a/0x570 net/core/net_namespace.c:118 setup_net+0x313/0x710 net/core/net_namespace.c:294 copy_net_ns+0x27c/0x580 net/core/net_namespace.c:418 create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206 SYSC_unshare kernel/fork.c:2347 [inline] SyS_unshare+0x653/0xfa0 kernel/fork.c:2297 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4512c9 RSP: 002b:00007f21e0428c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 0000000000718150 RCX: 00000000004512c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000062020200 RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004b973d R13: 00000000ffffffff R14: 000000002001d000 R15: 00000000000002dd Code: 50 2b 34 82 c7 00 f1 f1 f1 f1 c7 40 04 04 f2 f2 f2 c7 40 08 f3 f3 f3 f3 e8 a1 43 39 ff 4c 89 f8 48 8b 95 70 ff ff ff 48 c1 e8 03 <0f> b6 0c 18 4c 89 f8 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85 RIP: __read_once_size include/linux/compiler.h:250 [inline] RSP: ffff8801c6e5f1b0 RIP: atomic_read arch/x86/include/asm/atomic.h:26 [inline] RSP: ffff8801c6e5f1b0 RIP: refcount_sub_and_test+0x7d/0x1b0 lib/refcount.c:178 RSP: ffff8801c6e5f1b0 ---[ end trace e441d046c6410d31 ]--- Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Based on a syzkaller report [1], I found that a per cpu allocation
failure in snmp6_alloc_dev() would then lead to NULL dereference in
ip6_route_dev_notify().

It seems this is a very old bug, thus no Fixes tag in this submission.

Let's add in6_dev_put_clear() helper, as we will probably use
it elsewhere (once available/present in net-next)

[1]
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 17294 Comm: syz-executor6 Not tainted 4.13.0-rc2+ #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88019f456680 task.stack: ffff8801c6e58000
RIP: 0010:__read_once_size include/linux/compiler.h:250 [inline]
RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:26 [inline]
RIP: 0010:refcount_sub_and_test+0x7d/0x1b0 lib/refcount.c:178
RSP: 0018:ffff8801c6e5f1b0 EFLAGS: 00010202
RAX: 0000000000000037 RBX: dffffc0000000000 RCX: ffffc90005d25000
RDX: ffff8801c6e5f218 RSI: ffffffff82342bbf RDI: 0000000000000001
RBP: ffff8801c6e5f240 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff10038dcbe37
R13: 0000000000000006 R14: 0000000000000001 R15: 00000000000001b8
FS:  00007f21e0429700(0000) GS:ffff8801dc100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001ddbc22000 CR3: 00000001d632b000 CR4: 00000000001426e0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 refcount_dec_and_test+0x1a/0x20 lib/refcount.c:211
 in6_dev_put include/net/addrconf.h:335 [inline]
 ip6_route_dev_notify+0x1c9/0x4a0 net/ipv6/route.c:3732
 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1678
 call_netdevice_notifiers net/core/dev.c:1694 [inline]
 rollback_registered_many+0x91c/0xe80 net/core/dev.c:7107
 rollback_registered+0x1be/0x3c0 net/core/dev.c:7149
 register_netdevice+0xbcd/0xee0 net/core/dev.c:7587
 register_netdev+0x1a/0x30 net/core/dev.c:7669
 loopback_net_init+0x76/0x160 drivers/net/loopback.c:214
 ops_init+0x10a/0x570 net/core/net_namespace.c:118
 setup_net+0x313/0x710 net/core/net_namespace.c:294
 copy_net_ns+0x27c/0x580 net/core/net_namespace.c:418
 create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
 SYSC_unshare kernel/fork.c:2347 [inline]
 SyS_unshare+0x653/0xfa0 kernel/fork.c:2297
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x4512c9
RSP: 002b:00007f21e0428c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 0000000000718150 RCX: 00000000004512c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000062020200
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004b973d
R13: 00000000ffffffff R14: 000000002001d000 R15: 00000000000002dd
Code: 50 2b 34 82 c7 00 f1 f1 f1 f1 c7 40 04 04 f2 f2 f2 c7 40 08 f3 f3
f3 f3 e8 a1 43 39 ff 4c 89 f8 48 8b 95 70 ff ff ff 48 c1 e8 03 <0f> b6
0c 18 4c 89 f8 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85
RIP: __read_once_size include/linux/compiler.h:250 [inline] RSP:
ffff8801c6e5f1b0
RIP: atomic_read arch/x86/include/asm/atomic.h:26 [inline] RSP:
ffff8801c6e5f1b0
RIP: refcount_sub_and_test+0x7d/0x1b0 lib/refcount.c:178 RSP:
ffff8801c6e5f1b0
---[ end trace e441d046c6410d31 ]---

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Merge tag 'wireless-drivers-for-davem-2017-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers 2017-08-15T17:19:14+00:00 David S. Miller davem@davemloft.net 2017-08-15T17:19:14+00:00 0a6f04184d3d9c21cb6aa12140732aac6930922a Kalle Valo says: ==================== wireless-drivers fixes for 4.13 This time quite a few fixes for iwlwifi and one major regression fix for brcmfmac. For the iwlwifi aggregation bug a small change was needed for mac80211, but as Johannes is still away the mac80211 patch is taken via wireless-drivers tree. brcmfmac * fix firmware crash (a recent regression in bcm4343{0,1,8} iwlwifi * Some simple PCI HW ID fix-ups and additions for family 9000 * Remove a bogus warning message with new FWs (bug #196915) * Don't allow illegal channel options to be used (bug #195299) * A fix for checksum offload in family 9000 * A fix serious throughput degradation in 11ac with multiple streams * An old bug in SMPS where the firmware was not aware of SMPS changes * Fix a memory leak in the SAR code * Fix a stuck queue case in AP mode; * Convert a WARN to a simple debug in a legitimate race case (from which we can recover) * Fix a severe throughput aggregation on 9000-family devices due to aggregation issues, needed a small change in mac80211 ==================== Signed-off-by: David S. Miller <davem@davemloft.net> 
Kalle Valo says:

====================
wireless-drivers fixes for 4.13

This time quite a few fixes for iwlwifi and one major regression fix
for brcmfmac. For the iwlwifi aggregation bug a small change was
needed for mac80211, but as Johannes is still away the mac80211 patch
is taken via wireless-drivers tree.

brcmfmac

* fix firmware crash (a recent regression in bcm4343{0,1,8}

iwlwifi

* Some simple PCI HW ID fix-ups and additions for family 9000

* Remove a bogus warning message with new FWs (bug #196915)

* Don't allow illegal channel options to be used (bug #195299)

* A fix for checksum offload in family 9000

* A fix serious throughput degradation in 11ac with multiple streams

* An old bug in SMPS where the firmware was not aware of SMPS changes

* Fix a memory leak in the SAR code

* Fix a stuck queue case in AP mode;

* Convert a WARN to a simple debug in a legitimate race case (from
  which we can recover)

* Fix a severe throughput aggregation on 9000-family devices due to
  aggregation issues, needed a small change in mac80211
====================

Signed-off-by: David S. Miller <davem@davemloft.net>