wifi: mac80211: fix mesh fast xmit path deletion UAF

Overview

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: fix mesh fast xmit path deletion UAF

mesh_fast_tx_cache() stores raw mesh_path pointers. Path deletion flushes the cache and then frees the path with kfree_rcu(), but a lookup that already holds the path can insert a new cache entry after the flush. The cache then points at freed memory.

Set MESH_PATH_DELETED before flushing, and skip inserting a cache entry if the path or MPP path is already deleted. Check this under the cache walk lock so it is ordered with the flush. Use WRITE_ONCE() for the deletion flag updates because the cache check reads flags without taking state_lock.

Affected

• Linux >= d5edb9ae8d568745f893c5c5fa3837d85311b131 < 0117f1aa189495e6f1ff608681678817995aee39
• Linux >= d5edb9ae8d568745f893c5c5fa3837d85311b131 < 128e800a41270ab197b1cc8043637a2924865608
• Linux >= d5edb9ae8d568745f893c5c5fa3837d85311b131 < 93da3ec938bfdcfb3899428f04c6d0c56fe32952
• Linux >= d5edb9ae8d568745f893c5c5fa3837d85311b131 < ee3aadc43ea69d98f666431e787137ac0badbb85
• Linux 6.4

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.