UBUNTU-CVE-2026-80845

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UBUNTU-CVE-2026-80845

Summary:

Details: In the Linux kernel, the following vulnerability has been resolved: xfrm: avoid lock inversion in nat keepalive work nat_keepalive_work() walks the state table while xfrm_state_walk() holds net->xfrm.xfrm_state_lock. Its callback then acquires x->lock, which conflicts with the delete path taking the same locks in reverse order via xfrm_state_delete() and __xfrm_state_delete(). This creates an AB-BA deadlock that is reported by lockdep when a NAT keepalive worker races with SA deletion. Fix this by splitting the keepalive walk into two phases. First, collect the candidate states while the walk holds xfrm_state_lock and take a reference on each state. Then, after the walk completes, process each collected state and acquire x->lock without nesting it under xfrm_state_lock.

References: https://ubuntu.com/security/CVE-2026-80845, https://www.cve.org/CVERecord?id=CVE-2026-80845, https://git.kernel.org/linus/763fe700b7c58ad64fe5202c5638848244dd4127