Wind River Support Network

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.