Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix use-after-free due to MST port state bypass syzbot reported[1] a use-after-free when deleting an expired fdb. It is due to a race condition between learning still happening and a port being deleted, after all its fdbs have been flushed. The port's state has been toggled to disabled so no learning should happen at that time, but if we have MST enabled, it will bypass the port's state, that together with VLAN filtering disabled can lead to fdb learning at a time when it shouldn't happen while the port is being deleted. VLAN filtering must be disabled because we flush the port VLANs when it's being deleted which will stop learning. This fix adds a check for the port's vlan group which is initialized to NULL when the port is getting deleted, that avoids the port state bypass. When MST is enabled there would be a minimal new overhead in the fast-path because the port's vlan group pointer is cache-hot. [1] https://syzkaller.appspot.com/bug?extid=dd280197f0f7ab3917be
References
- https://git.kernel.org/stable/c/3b60ce334c1ce8b3fad7e02dcd5ed9f6646477c8
- https://git.kernel.org/stable/c/8dca36978aa80bab9d4da130c211db75c9e00048
- https://git.kernel.org/stable/c/991fbe1680cd41a5f97c92cd3a3496315df36e4b
- https://git.kernel.org/stable/c/bf3843183bc3158e5821b46f330c438ae9bd6ddb
- https://git.kernel.org/stable/c/e19085b2a86addccff33ab8536fc67ebd9d52198
FAQ
What is CVE-2025-40297?
CVE-2025-40297 is a documented vulnerability. In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix use-after-free due to MST port state bypass syzbot reported[1] a use-after-free when deleting an expired fdb. It ...
How severe is CVE-2025-40297?
CVSS scoring is not yet available for CVE-2025-40297. Check NVD for updates.
Is there a patch for CVE-2025-40297?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.