CVE-2026-68409

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

wifi: mac80211: defer link RX stats percpu free to RCU

sta_remove_link() frees a removed MLO links RX stats percpu buffer right away, but defers only the link container to RCU:

sta_info_free_link(&alloc->info);
kfree_rcu(alloc, rcu_head);

The RX fast path reads link_sta under rcu_read_lock and writes the percpu stats. A reader that resolved link_sta before the removal keeps the pointer. The container stays alive from the kfree_rcu, so the read still works. But the percpu block it points to is already freed. This needs uses_rss. That is when pcpu_rx_stats exists.

The full STA teardown frees the deflink stats only after synchronize_net(). The link removal path had no such barrier. The race is hard to win in practice, but the free should still wait for RCU.

Free the link together with its data from a single RCU callback, so the percpu block is reclaimed only after readers drain.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/2aa1789880fa5e41049b0f6a74a4fc2fa1997610
• https://git.kernel.org/stable/c/a03fceae0c65b31ce31840dac5e26684ceecb65b
• https://git.kernel.org/stable/c/a5afc00280986063f1c355821544fabbb2a960f7
• https://git.kernel.org/stable/c/aa2eb62525188269cdd402a583b9a8ed94657ff0
• https://git.kernel.org/stable/c/acd5931d5adf12f0163f83dc00320e7011f4da92
• https://git.kernel.org/stable/c/b679c1cffb2f3d0854b8b05ea9e909ad6489046f