* [PATCH net] sock_map: avoid race between sock_map_close and sk_psock_put
@ 2024-05-20 21:41 Thadeu Lima de Souza Cascardo
2024-05-22 12:08 ` Paolo Abeni
0 siblings, 1 reply; 4+ messages in thread
From: Thadeu Lima de Souza Cascardo @ 2024-05-20 21:41 UTC (permalink / raw)
To: netdev
Cc: Cong Wang, Jakub Sitnicki, Eric Dumazet, Daniel Borkmann,
John Fastabend, David S. Miller, Jakub Kicinski,
Alexei Starovoitov, Paolo Abeni, bpf, kernel-dev,
Thadeu Lima de Souza Cascardo, syzbot+07a2e4a1a57118ef7355,
stable
sk_psock_get will return NULL if the refcount of psock has gone to 0, which
will happen when the last call of sk_psock_put is done. However,
sk_psock_drop may not have finished yet, so the close callback will still
point to sock_map_close despite psock being NULL.
This can be reproduced with a thread deleting an element from the sock map,
while the second one creates a socket, adds it to the map and closes it.
That will trigger the WARN_ON_ONCE:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 7220 at net/core/sock_map.c:1701 sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
Modules linked in:
CPU: 1 PID: 7220 Comm: syz-executor380 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
Code: df e8 92 29 88 f8 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 79 29 88 f8 4c 8b 23 eb 89 e8 4f 15 23 f8 90 <0f> 0b 90 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 13 26 3d 02
RSP: 0018:ffffc9000441fda8 EFLAGS: 00010293
RAX: ffffffff89731ae1 RBX: ffffffff94b87540 RCX: ffff888029470000
RDX: 0000000000000000 RSI: ffffffff8bcab5c0 RDI: ffffffff8c1faba0
RBP: 0000000000000000 R08: ffffffff92f9b61f R09: 1ffffffff25f36c3
R10: dffffc0000000000 R11: fffffbfff25f36c4 R12: ffffffff89731840
R13: ffff88804b587000 R14: ffff88804b587000 R15: ffffffff89731870
FS: 000055555e080380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000207d4000 CR4: 0000000000350ef0
Call Trace:
<TASK>
unix_release+0x87/0xc0 net/unix/af_unix.c:1048
__sock_release net/socket.c:659 [inline]
sock_close+0xbe/0x240 net/socket.c:1421
__fput+0x42b/0x8a0 fs/file_table.c:422
__do_sys_close fs/open.c:1556 [inline]
__se_sys_close fs/open.c:1541 [inline]
__x64_sys_close+0x7f/0x110 fs/open.c:1541
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb37d618070
Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 10 2c 00 00 80 3d 31 f0 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
RSP: 002b:00007ffcd4a525d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fb37d618070
RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000100000000 R09: 0000000100000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Use sk_psock, which will only check that the pointer is not been set to
NULL yet, which should only happen after the callbacks are restored. If,
then, a reference can still be gotten, we may call sk_psock_stop and cancel
psock->work.
After that change, the reproducer does not trigger the WARN_ON_ONCE
anymore.
Reported-by: syzbot+07a2e4a1a57118ef7355@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=07a2e4a1a57118ef7355
Fixes: aadb2bb83ff7 ("sock_map: Fix a potential use-after-free in sock_map_close()")
Fixes: 5b4a79ba65a1 ("bpf, sockmap: Don't let sock_map_{close,destroy,unhash} call itself")
Cc: stable@vger.kernel.org
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
---
net/core/sock_map.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 9402889840bf..13267e667a4c 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1680,19 +1680,23 @@ void sock_map_close(struct sock *sk, long timeout)
lock_sock(sk);
rcu_read_lock();
- psock = sk_psock_get(sk);
+ psock = sk_psock(sk);
if (unlikely(!psock)) {
+ saved_close = READ_ONCE(sk->sk_prot)->close;
rcu_read_unlock();
release_sock(sk);
- saved_close = READ_ONCE(sk->sk_prot)->close;
} else {
saved_close = psock->saved_close;
sock_map_remove_links(sk, psock);
+ psock = sk_psock_get(sk);
rcu_read_unlock();
- sk_psock_stop(psock);
+ if (psock)
+ sk_psock_stop(psock);
release_sock(sk);
- cancel_delayed_work_sync(&psock->work);
- sk_psock_put(sk, psock);
+ if (psock) {
+ cancel_delayed_work_sync(&psock->work);
+ sk_psock_put(sk, psock);
+ }
}
/* Make sure we do not recurse. This is a bug.
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH net] sock_map: avoid race between sock_map_close and sk_psock_put
2024-05-20 21:41 [PATCH net] sock_map: avoid race between sock_map_close and sk_psock_put Thadeu Lima de Souza Cascardo
@ 2024-05-22 12:08 ` Paolo Abeni
2024-05-23 7:52 ` Paolo Abeni
0 siblings, 1 reply; 4+ messages in thread
From: Paolo Abeni @ 2024-05-22 12:08 UTC (permalink / raw)
To: Thadeu Lima de Souza Cascardo, netdev
Cc: Cong Wang, Jakub Sitnicki, Eric Dumazet, Daniel Borkmann,
John Fastabend, David S. Miller, Jakub Kicinski,
Alexei Starovoitov, bpf, kernel-dev, syzbot+07a2e4a1a57118ef7355,
stable
On Mon, 2024-05-20 at 18:41 -0300, Thadeu Lima de Souza Cascardo wrote:
> sk_psock_get will return NULL if the refcount of psock has gone to 0, which
> will happen when the last call of sk_psock_put is done. However,
> sk_psock_drop may not have finished yet, so the close callback will still
> point to sock_map_close despite psock being NULL.
>
> This can be reproduced with a thread deleting an element from the sock map,
> while the second one creates a socket, adds it to the map and closes it.
>
> That will trigger the WARN_ON_ONCE:
>
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 7220 at net/core/sock_map.c:1701 sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
> Modules linked in:
> CPU: 1 PID: 7220 Comm: syz-executor380 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
> RIP: 0010:sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
> Code: df e8 92 29 88 f8 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 79 29 88 f8 4c 8b 23 eb 89 e8 4f 15 23 f8 90 <0f> 0b 90 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 13 26 3d 02
> RSP: 0018:ffffc9000441fda8 EFLAGS: 00010293
> RAX: ffffffff89731ae1 RBX: ffffffff94b87540 RCX: ffff888029470000
> RDX: 0000000000000000 RSI: ffffffff8bcab5c0 RDI: ffffffff8c1faba0
> RBP: 0000000000000000 R08: ffffffff92f9b61f R09: 1ffffffff25f36c3
> R10: dffffc0000000000 R11: fffffbfff25f36c4 R12: ffffffff89731840
> R13: ffff88804b587000 R14: ffff88804b587000 R15: ffffffff89731870
> FS: 000055555e080380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 00000000207d4000 CR4: 0000000000350ef0
> Call Trace:
> <TASK>
> unix_release+0x87/0xc0 net/unix/af_unix.c:1048
> __sock_release net/socket.c:659 [inline]
> sock_close+0xbe/0x240 net/socket.c:1421
> __fput+0x42b/0x8a0 fs/file_table.c:422
> __do_sys_close fs/open.c:1556 [inline]
> __se_sys_close fs/open.c:1541 [inline]
> __x64_sys_close+0x7f/0x110 fs/open.c:1541
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fb37d618070
> Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 10 2c 00 00 80 3d 31 f0 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
> RSP: 002b:00007ffcd4a525d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
> RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fb37d618070
> RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004
> RBP: 0000000000000000 R08: 0000000100000000 R09: 0000000100000000
> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> </TASK>
>
> Use sk_psock, which will only check that the pointer is not been set to
> NULL yet, which should only happen after the callbacks are restored. If,
> then, a reference can still be gotten, we may call sk_psock_stop and cancel
> psock->work.
>
> After that change, the reproducer does not trigger the WARN_ON_ONCE
> anymore.
>
> Reported-by: syzbot+07a2e4a1a57118ef7355@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=07a2e4a1a57118ef7355
> Fixes: aadb2bb83ff7 ("sock_map: Fix a potential use-after-free in sock_map_close()")
> Fixes: 5b4a79ba65a1 ("bpf, sockmap: Don't let sock_map_{close,destroy,unhash} call itself")
> Cc: stable@vger.kernel.org
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
> ---
> net/core/sock_map.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/net/core/sock_map.c b/net/core/sock_map.c
> index 9402889840bf..13267e667a4c 100644
> --- a/net/core/sock_map.c
> +++ b/net/core/sock_map.c
> @@ -1680,19 +1680,23 @@ void sock_map_close(struct sock *sk, long timeout)
>
> lock_sock(sk);
> rcu_read_lock();
> - psock = sk_psock_get(sk);
> + psock = sk_psock(sk);
> if (unlikely(!psock)) {
> + saved_close = READ_ONCE(sk->sk_prot)->close;
> rcu_read_unlock();
> release_sock(sk);
> - saved_close = READ_ONCE(sk->sk_prot)->close;
> } else {
> saved_close = psock->saved_close;
> sock_map_remove_links(sk, psock);
> + psock = sk_psock_get(sk);
> rcu_read_unlock();
> - sk_psock_stop(psock);
> + if (psock)
> + sk_psock_stop(psock);
> release_sock(sk);
> - cancel_delayed_work_sync(&psock->work);
> - sk_psock_put(sk, psock);
> + if (psock) {
> + cancel_delayed_work_sync(&psock->work);
> + sk_psock_put(sk, psock);
> + }
> }
>
> /* Make sure we do not recurse. This is a bug.
As a personal opinion I think the code will become simple reordering
the condition, something alike:
if (psock) {
saved_close = psock->saved_close;
sock_map_remove_links(sk, psock);
psock = sk_psock_get(sk);
if (!psock)
goto no_psock;
rcu_read_unlock();
sk_psock_stop(psock);
release_sock(sk);
cancel_delayed_work_sync(&psock->work);
sk_psock_put(sk, psock);
} else {
no_psock:
saved_close = READ_ONCE(sk->sk_prot)->close;
rcu_read_unlock();
release_sock(sk);
}
Overall looks safe to me, but I would appreciate an explicit ack from
Jakub S. or John.
Cheers,
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] sock_map: avoid race between sock_map_close and sk_psock_put
2024-05-22 12:08 ` Paolo Abeni
@ 2024-05-23 7:52 ` Paolo Abeni
2024-05-23 9:20 ` Jakub Sitnicki
0 siblings, 1 reply; 4+ messages in thread
From: Paolo Abeni @ 2024-05-23 7:52 UTC (permalink / raw)
To: Thadeu Lima de Souza Cascardo, netdev
Cc: Cong Wang, Jakub Sitnicki, Eric Dumazet, Daniel Borkmann,
John Fastabend, David S. Miller, Jakub Kicinski,
Alexei Starovoitov, bpf, kernel-dev, syzbot+07a2e4a1a57118ef7355,
stable
On Wed, 2024-05-22 at 14:08 +0200, Paolo Abeni wrote:
> On Mon, 2024-05-20 at 18:41 -0300, Thadeu Lima de Souza Cascardo wrote:
> > sk_psock_get will return NULL if the refcount of psock has gone to 0, which
> > will happen when the last call of sk_psock_put is done. However,
> > sk_psock_drop may not have finished yet, so the close callback will still
> > point to sock_map_close despite psock being NULL.
> >
> > This can be reproduced with a thread deleting an element from the sock map,
> > while the second one creates a socket, adds it to the map and closes it.
> >
> > That will trigger the WARN_ON_ONCE:
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 1 PID: 7220 at net/core/sock_map.c:1701 sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
> > Modules linked in:
> > CPU: 1 PID: 7220 Comm: syz-executor380 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
> > RIP: 0010:sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
> > Code: df e8 92 29 88 f8 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 79 29 88 f8 4c 8b 23 eb 89 e8 4f 15 23 f8 90 <0f> 0b 90 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 13 26 3d 02
> > RSP: 0018:ffffc9000441fda8 EFLAGS: 00010293
> > RAX: ffffffff89731ae1 RBX: ffffffff94b87540 RCX: ffff888029470000
> > RDX: 0000000000000000 RSI: ffffffff8bcab5c0 RDI: ffffffff8c1faba0
> > RBP: 0000000000000000 R08: ffffffff92f9b61f R09: 1ffffffff25f36c3
> > R10: dffffc0000000000 R11: fffffbfff25f36c4 R12: ffffffff89731840
> > R13: ffff88804b587000 R14: ffff88804b587000 R15: ffffffff89731870
> > FS: 000055555e080380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000000000 CR3: 00000000207d4000 CR4: 0000000000350ef0
> > Call Trace:
> > <TASK>
> > unix_release+0x87/0xc0 net/unix/af_unix.c:1048
> > __sock_release net/socket.c:659 [inline]
> > sock_close+0xbe/0x240 net/socket.c:1421
> > __fput+0x42b/0x8a0 fs/file_table.c:422
> > __do_sys_close fs/open.c:1556 [inline]
> > __se_sys_close fs/open.c:1541 [inline]
> > __x64_sys_close+0x7f/0x110 fs/open.c:1541
> > do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
> > entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > RIP: 0033:0x7fb37d618070
> > Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 10 2c 00 00 80 3d 31 f0 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
> > RSP: 002b:00007ffcd4a525d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
> > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fb37d618070
> > RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004
> > RBP: 0000000000000000 R08: 0000000100000000 R09: 0000000100000000
> > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> > </TASK>
> >
> > Use sk_psock, which will only check that the pointer is not been set to
> > NULL yet, which should only happen after the callbacks are restored. If,
> > then, a reference can still be gotten, we may call sk_psock_stop and cancel
> > psock->work.
> >
> > After that change, the reproducer does not trigger the WARN_ON_ONCE
> > anymore.
> >
> > Reported-by: syzbot+07a2e4a1a57118ef7355@syzkaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=07a2e4a1a57118ef7355
> > Fixes: aadb2bb83ff7 ("sock_map: Fix a potential use-after-free in sock_map_close()")
> > Fixes: 5b4a79ba65a1 ("bpf, sockmap: Don't let sock_map_{close,destroy,unhash} call itself")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
> > ---
> > net/core/sock_map.c | 14 +++++++++-----
> > 1 file changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/net/core/sock_map.c b/net/core/sock_map.c
> > index 9402889840bf..13267e667a4c 100644
> > --- a/net/core/sock_map.c
> > +++ b/net/core/sock_map.c
> > @@ -1680,19 +1680,23 @@ void sock_map_close(struct sock *sk, long timeout)
> >
> > lock_sock(sk);
> > rcu_read_lock();
> > - psock = sk_psock_get(sk);
> > + psock = sk_psock(sk);
> > if (unlikely(!psock)) {
> > + saved_close = READ_ONCE(sk->sk_prot)->close;
> > rcu_read_unlock();
> > release_sock(sk);
> > - saved_close = READ_ONCE(sk->sk_prot)->close;
> > } else {
> > saved_close = psock->saved_close;
> > sock_map_remove_links(sk, psock);
> > + psock = sk_psock_get(sk);
> > rcu_read_unlock();
> > - sk_psock_stop(psock);
> > + if (psock)
> > + sk_psock_stop(psock);
> > release_sock(sk);
> > - cancel_delayed_work_sync(&psock->work);
> > - sk_psock_put(sk, psock);
> > + if (psock) {
> > + cancel_delayed_work_sync(&psock->work);
> > + sk_psock_put(sk, psock);
> > + }
> > }
> >
> > /* Make sure we do not recurse. This is a bug.
>
> As a personal opinion I think the code will become simple reordering
> the condition, something alike:
>
> if (psock) {
> saved_close = psock->saved_close;
> sock_map_remove_links(sk, psock);
> psock = sk_psock_get(sk);
> if (!psock)
> goto no_psock;
> rcu_read_unlock();
> sk_psock_stop(psock);
> release_sock(sk);
> cancel_delayed_work_sync(&psock->work);
> sk_psock_put(sk, psock);
> } else {
> no_psock:
> saved_close = READ_ONCE(sk->sk_prot)->close;
FTR, the above is wrong, should be:
saved_close = READ_ONCE(sk->sk_prot)->close;
no_psock:
> rcu_read_unlock();
> release_sock(sk);
> }
/P
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] sock_map: avoid race between sock_map_close and sk_psock_put
2024-05-23 7:52 ` Paolo Abeni
@ 2024-05-23 9:20 ` Jakub Sitnicki
0 siblings, 0 replies; 4+ messages in thread
From: Jakub Sitnicki @ 2024-05-23 9:20 UTC (permalink / raw)
To: Paolo Abeni
Cc: Thadeu Lima de Souza Cascardo, netdev, Cong Wang, Eric Dumazet,
Daniel Borkmann, John Fastabend, David S. Miller, Jakub Kicinski,
Alexei Starovoitov, bpf, kernel-dev, syzbot+07a2e4a1a57118ef7355,
stable
On Thu, May 23, 2024 at 09:52 AM +02, Paolo Abeni wrote:
> On Wed, 2024-05-22 at 14:08 +0200, Paolo Abeni wrote:
>> On Mon, 2024-05-20 at 18:41 -0300, Thadeu Lima de Souza Cascardo wrote:
>> > sk_psock_get will return NULL if the refcount of psock has gone to 0, which
>> > will happen when the last call of sk_psock_put is done. However,
>> > sk_psock_drop may not have finished yet, so the close callback will still
>> > point to sock_map_close despite psock being NULL.
>> >
>> > This can be reproduced with a thread deleting an element from the sock map,
>> > while the second one creates a socket, adds it to the map and closes it.
>> >
>> > That will trigger the WARN_ON_ONCE:
>> >
>> > ------------[ cut here ]------------
>> > WARNING: CPU: 1 PID: 7220 at net/core/sock_map.c:1701 sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
>> > Modules linked in:
>> > CPU: 1 PID: 7220 Comm: syz-executor380 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0
>> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
>> > RIP: 0010:sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701
>> > Code: df e8 92 29 88 f8 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 79 29 88 f8 4c 8b 23 eb 89 e8 4f 15 23 f8 90 <0f> 0b 90 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 13 26 3d 02
>> > RSP: 0018:ffffc9000441fda8 EFLAGS: 00010293
>> > RAX: ffffffff89731ae1 RBX: ffffffff94b87540 RCX: ffff888029470000
>> > RDX: 0000000000000000 RSI: ffffffff8bcab5c0 RDI: ffffffff8c1faba0
>> > RBP: 0000000000000000 R08: ffffffff92f9b61f R09: 1ffffffff25f36c3
>> > R10: dffffc0000000000 R11: fffffbfff25f36c4 R12: ffffffff89731840
>> > R13: ffff88804b587000 R14: ffff88804b587000 R15: ffffffff89731870
>> > FS: 000055555e080380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
>> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> > CR2: 0000000000000000 CR3: 00000000207d4000 CR4: 0000000000350ef0
>> > Call Trace:
>> > <TASK>
>> > unix_release+0x87/0xc0 net/unix/af_unix.c:1048
>> > __sock_release net/socket.c:659 [inline]
>> > sock_close+0xbe/0x240 net/socket.c:1421
>> > __fput+0x42b/0x8a0 fs/file_table.c:422
>> > __do_sys_close fs/open.c:1556 [inline]
>> > __se_sys_close fs/open.c:1541 [inline]
>> > __x64_sys_close+0x7f/0x110 fs/open.c:1541
>> > do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>> > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
>> > entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> > RIP: 0033:0x7fb37d618070
>> > Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 10 2c 00 00 80 3d 31 f0 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c
>> > RSP: 002b:00007ffcd4a525d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
>> > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fb37d618070
>> > RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004
>> > RBP: 0000000000000000 R08: 0000000100000000 R09: 0000000100000000
>> > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
>> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>> > </TASK>
>> >
>> > Use sk_psock, which will only check that the pointer is not been set to
>> > NULL yet, which should only happen after the callbacks are restored. If,
>> > then, a reference can still be gotten, we may call sk_psock_stop and cancel
>> > psock->work.
>> >
>> > After that change, the reproducer does not trigger the WARN_ON_ONCE
>> > anymore.
>> >
>> > Reported-by: syzbot+07a2e4a1a57118ef7355@syzkaller.appspotmail.com
>> > Closes: https://syzkaller.appspot.com/bug?extid=07a2e4a1a57118ef7355
>> > Fixes: aadb2bb83ff7 ("sock_map: Fix a potential use-after-free in sock_map_close()")
>> > Fixes: 5b4a79ba65a1 ("bpf, sockmap: Don't let sock_map_{close,destroy,unhash} call itself")
>> > Cc: stable@vger.kernel.org
>> > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
>> > ---
>> > net/core/sock_map.c | 14 +++++++++-----
>> > 1 file changed, 9 insertions(+), 5 deletions(-)
>> >
>> > diff --git a/net/core/sock_map.c b/net/core/sock_map.c
>> > index 9402889840bf..13267e667a4c 100644
>> > --- a/net/core/sock_map.c
>> > +++ b/net/core/sock_map.c
>> > @@ -1680,19 +1680,23 @@ void sock_map_close(struct sock *sk, long timeout)
>> >
>> > lock_sock(sk);
>> > rcu_read_lock();
>> > - psock = sk_psock_get(sk);
>> > + psock = sk_psock(sk);
>> > if (unlikely(!psock)) {
>> > + saved_close = READ_ONCE(sk->sk_prot)->close;
>> > rcu_read_unlock();
>> > release_sock(sk);
>> > - saved_close = READ_ONCE(sk->sk_prot)->close;
>> > } else {
>> > saved_close = psock->saved_close;
>> > sock_map_remove_links(sk, psock);
>> > + psock = sk_psock_get(sk);
>> > rcu_read_unlock();
>> > - sk_psock_stop(psock);
>> > + if (psock)
>> > + sk_psock_stop(psock);
>> > release_sock(sk);
>> > - cancel_delayed_work_sync(&psock->work);
>> > - sk_psock_put(sk, psock);
>> > + if (psock) {
>> > + cancel_delayed_work_sync(&psock->work);
>> > + sk_psock_put(sk, psock);
>> > + }
>> > }
>> >
>> > /* Make sure we do not recurse. This is a bug.
>>
>> As a personal opinion I think the code will become simple reordering
>> the condition, something alike:
>>
>> if (psock) {
>> saved_close = psock->saved_close;
>> sock_map_remove_links(sk, psock);
>> psock = sk_psock_get(sk);
>> if (!psock)
>> goto no_psock;
>> rcu_read_unlock();
>> sk_psock_stop(psock);
>> release_sock(sk);
>> cancel_delayed_work_sync(&psock->work);
>> sk_psock_put(sk, psock);
>> } else {
>> no_psock:
>> saved_close = READ_ONCE(sk->sk_prot)->close;
>
> FTR, the above is wrong, should be:
>
> saved_close = READ_ONCE(sk->sk_prot)->close;
> no_psock:
>
>> rcu_read_unlock();
>> release_sock(sk);
>> }
>
> /P
Paolo's version does read better to me as well.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-05-23 9:20 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-05-20 21:41 [PATCH net] sock_map: avoid race between sock_map_close and sk_psock_put Thadeu Lima de Souza Cascardo
2024-05-22 12:08 ` Paolo Abeni
2024-05-23 7:52 ` Paolo Abeni
2024-05-23 9:20 ` Jakub Sitnicki
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