From: Michal Luczaj <mhal@rbox.co> stable inclusion from stable-v6.6.79 commit f3b8e9d3414b2eb083d8293be25a949fe480897b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBPC5N CVE: CVE-2025-21756 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ------------------------------------------------- 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Liu Jian <liujian56@huawei.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 34bed66a8d25..cf3d3cbb64a0 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -814,13 +814,19 @@ 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); -- 2.34.1