[PATCH net 2/3] vsock: Fix transport_g2h TOCTOU
From: Michal Luczaj <hidden>
Date: 2025-06-18 12:34:53
Also in:
lkml, virtualization
Subsystem:
networking [general], the rest, vm sockets (af_vsock) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Stefano Garzarella
Function may race with vsock_core_unregister(): transport_g2h may become
NULL after the NULL check. Protect from a potential null-ptr-deref.
KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f]
RIP: 0010:vsock_find_cid+0x47/0x90
Call Trace:
__vsock_bind+0x4b2/0x720
vsock_bind+0x90/0xe0
__sys_bind+0x14d/0x1e0
__x64_sys_bind+0x6e/0xc0
do_syscall_64+0x92/0x1c0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
Signed-off-by: Michal Luczaj <redacted>
---
net/vmw_vsock/af_vsock.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 047d1bc773fab9c315a6ccd383a451fa11fb703e..337540efc237c8bc482a6730948fc773c00854f1 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c@@ -533,8 +533,10 @@ EXPORT_SYMBOL_GPL(vsock_assign_transport); bool vsock_find_cid(unsigned int cid) { - if (transport_g2h && cid == transport_g2h->get_local_cid()) - return true; + scoped_guard(mutex, &vsock_register_mutex) { + if (transport_g2h && cid == transport_g2h->get_local_cid()) + return true; + } if (transport_h2g && cid == VMADDR_CID_HOST) return true;
--
2.49.0