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vsock: Orphan socket after transport release

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During socket release, sock_orphan() is called without considering that it
sets sk->sk_wq to NULL. Later, if SO_LINGER is enabled, this leads to a
null pointer dereferenced in virtio_transport_wait_close().

Orphan the socket only after transport release.

Partially reverts the 'Fixes:' commit.

KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
 lock_acquire+0x19e/0x500
 _raw_spin_lock_irqsave+0x47/0x70
 add_wait_queue+0x46/0x230
 virtio_transport_release+0x4e7/0x7f0
 __vsock_release+0xfd/0x490
 vsock_release+0x90/0x120
 __sock_release+0xa3/0x250
 sock_close+0x14/0x20
 __fput+0x35e/0xa90
 __x64_sys_close+0x78/0xd0
 do_syscall_64+0x93/0x1b0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Reported-by: syzbot+9d55b199192a4be7d02c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9d55b199192a4be7d02c
Fixes: fcdd2242c0 ("vsock: Keep the binding until socket destruction")
Tested-by: Luigi Leonardi <leonardi@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://patch.msgid.link/20250210-vsock-linger-nullderef-v3-1-ef6244d02b54@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Michal Luczaj 2025-02-10 13:15:00 +01:00 • committed by Jakub Kicinski
parent 15d6f74f03
commit 78dafe1cf3
1 changed files with 7 additions and 1 deletions
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8
net/vmw_vsock/af_vsock.c
View file

@ -824,13 +824,19 @@ static void __vsock_release(struct sock *sk, int level)
*/
lock_sock_nested(sk, level);
sock_orphan(sk);
/* Indicate to vsock_remove_sock() that the socket is being released and
* can be removed from the bound_table. Unlike transport reassignment
* case, where the socket must remain bound despite vsock_remove_sock()
* being called from the transport release() callback.
*/
sock_set_flag(sk, SOCK_DEAD);
if (vsk->transport)
vsk->transport->release(vsk);
else if (sock_type_connectible(sk->sk_type))
vsock_remove_sock(vsk);
sock_orphan(sk);
sk->sk_shutdown = SHUTDOWN_MASK;
skb_queue_purge(&sk->sk_receive_queue);