From 524575b19059e20963d62f61d35fff41f9712c66 Mon Sep 17 00:00:00 2001 From: Roxana Nicolescu Date: Tue, 11 Nov 2025 15:18:34 +0100 Subject: [PATCH 1/2] vsock: reset socket state when de-assigning the transport jira VULN-80685 cve-bf CVE-2025-38461 commit-author Stefano Garzarella commit a24009bc9be60242651a21702609381b5092459e Transport's release() and destruct() are called when de-assigning the vsock transport. These callbacks can touch some socket state like sock flags, sk_state, and peer_shutdown. Since we are reassigning the socket to a new transport during vsock_connect(), let's reset these fields to have a clean state with the new transport. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Reviewed-by: Luigi Leonardi Signed-off-by: Paolo Abeni (cherry picked from commit a24009bc9be60242651a21702609381b5092459e) Signed-off-by: Roxana Nicolescu --- net/vmw_vsock/af_vsock.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index f60b3670490d8..345a5888152a9 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -498,6 +498,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) */ vsk->transport->release(vsk); vsock_deassign_transport(vsk); + + /* transport's release() and destruct() can touch some socket + * state, since we are reassigning the socket to a new transport + * during vsock_connect(), let's reset these fields to have a + * clean state. + */ + sock_reset_flag(sk, SOCK_DONE); + sk->sk_state = TCP_CLOSE; + vsk->peer_shutdown = 0; } /* We increase the module refcnt to prevent the transport unloading From 19e651a041e177ca1a32e26b735161a885c17a34 Mon Sep 17 00:00:00 2001 From: Roxana Nicolescu Date: Wed, 12 Nov 2025 15:03:18 +0100 Subject: [PATCH 2/2] vsock: fix lock inversion in vsock_assign_transport() jira VULN-80685 cve-bf CVE-2025-38461 commit-author Stefano Garzarella commit f7c877e7535260cc7a21484c994e8ce7e8cb6780 Syzbot reported a potential lock inversion deadlock between vsock_register_mutex and sk_lock-AF_VSOCK when vsock_linger() is called. The issue was introduced by commit 687aa0c5581b ("vsock: Fix transport_* TOCTOU") which added vsock_register_mutex locking in vsock_assign_transport() around the transport->release() call, that can call vsock_linger(). vsock_assign_transport() can be called with sk_lock held. vsock_linger() calls sk_wait_event() that temporarily releases and re-acquires sk_lock. During this window, if another thread hold vsock_register_mutex while trying to acquire sk_lock, a circular dependency is created. Fix this by releasing vsock_register_mutex before calling transport->release() and vsock_deassign_transport(). This is safe because we don't need to hold vsock_register_mutex while releasing the old transport, and we ensure the new transport won't disappear by obtaining a module reference first via try_module_get(). Reported-by: syzbot+10e35716f8e4929681fa@syzkaller.appspotmail.com Tested-by: syzbot+10e35716f8e4929681fa@syzkaller.appspotmail.com Fixes: 687aa0c5581b ("vsock: Fix transport_* TOCTOU") Cc: mhal@rbox.co Cc: stable@vger.kernel.org Signed-off-by: Stefano Garzarella Link: https://patch.msgid.link/20251021121718.137668-1-sgarzare@redhat.com Signed-off-by: Paolo Abeni (cherry picked from commit f7c877e7535260cc7a21484c994e8ce7e8cb6780) Signed-off-by: Roxana Nicolescu --- net/vmw_vsock/af_vsock.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 345a5888152a9..d19538b97489d 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -484,12 +484,26 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) goto err; } - if (vsk->transport) { - if (vsk->transport == new_transport) { - ret = 0; - goto err; - } + if (vsk->transport && vsk->transport == new_transport) { + ret = 0; + goto err; + } + /* We increase the module refcnt to prevent the transport unloading + * while there are open sockets assigned to it. + */ + if (!new_transport || !try_module_get(new_transport->module)) { + ret = -ENODEV; + goto err; + } + + /* It's safe to release the mutex after a successful try_module_get(). + * Whichever transport `new_transport` points at, it won't go away until + * the last module_put() below or in vsock_deassign_transport(). + */ + mutex_unlock(&vsock_register_mutex); + + if (vsk->transport) { /* transport->release() must be called with sock lock acquired. * This path can only be taken during vsock_connect(), where we * have already held the sock lock. In the other cases, this @@ -509,20 +523,6 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) vsk->peer_shutdown = 0; } - /* We increase the module refcnt to prevent the transport unloading - * while there are open sockets assigned to it. - */ - if (!new_transport || !try_module_get(new_transport->module)) { - ret = -ENODEV; - goto err; - } - - /* It's safe to release the mutex after a successful try_module_get(). - * Whichever transport `new_transport` points at, it won't go away until - * the last module_put() below or in vsock_deassign_transport(). - */ - mutex_unlock(&vsock_register_mutex); - if (sk->sk_type == SOCK_SEQPACKET) { if (!new_transport->seqpacket_allow || !new_transport->seqpacket_allow(remote_cid)) {