From: Michal Luczaj mhal@rbox.co
commit 78dafe1cf3afa02ed71084b350713b07e72a18fb upstream.
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: fcdd2242c023 ("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@r... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Luigi Leonardi leonardi@redhat.com --- net/vmw_vsock/af_vsock.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index f922c4681dd9075ab01d1783178f1fe4f491260c..c7a786c7420ab58934091c026537bf29fe9e8374 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -818,13 +818,19 @@ 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);