vsock: fix lock inversion in vsock_assign_transport()
Summary
vsock: fix lock inversion in vsock_assign_transport()
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
vsock: fix lock inversion in vsock_assign_transport()
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().
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2025-40231 linux-lts Fixed in: 6.1.158-r0
- Debian DEBIAN-CVE-2025-40231 linux Fixed in: 5.10.247-1
- Ubuntu UBUNTU-CVE-2025-40231 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org