CVE-2026-90046mm/page_alloc: don't spin_trylock() in NMI on UP

Official description

In the Linux kernel, the following vulnerability has been resolved: mm/page_alloc: don't spin_trylock() in NMI on UP Patch series "mm/page_alloc: fixes for free_pages_nolock() on RT/UP". Pre-existing bugs found by Sashiko during review of this other series: https://lore.kernel.org/all/20260703-alloc-trylock-v5-0-c87b714e19d3@google.com/ I have not reproduced these bugs, and I suspect there is no real-world user that is affected by them. This patch (of 2): As noted in can_spin_trylock(), using this is unsafe in this context. commit 620b46ed6ae17 ("mm/page_alloc: return NULL early from alloc_frozen_pages_nolock() in NMI on UP") fixed this on the alloc side but missed the free side. Impact: If BPF programs using these features in NMI (probably tracing) are present on non-SMP builds this might crash the kernel and is probably exploitable by local attackers for privilege escalation.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/06c76d3c389ff504052f64b1acee44651bd847fa
• https://git.kernel.org/stable/c/68a069b407303e71db371df85036101e8ff59280
• https://git.kernel.org/stable/c/3105ae628fb785d48b49256468be4f21a7b3cfc0