Bug 2461552 (CVE-2026-31567)

Summary: CVE-2026-31567 kernel: PM: sleep: Drop spurious WARN_ON() from pm_restore_gfp_mask()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel. When the `pm_restore_gfp_mask()` function is invoked during certain hibernation processes, it can erroneously trigger a warning. This leads to the generation of spurious (false) warning messages in system logs, which may obscure legitimate issues and cause minor operational overhead.
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Description OSIDB Bzimport 2026-04-24 15:08:04 UTC
In the Linux kernel, the following vulnerability has been resolved:

PM: sleep: Drop spurious WARN_ON() from pm_restore_gfp_mask()

Commit 35e4a69b2003f ("PM: sleep: Allow pm_restrict_gfp_mask()
stacking") introduced refcount-based GFP mask management that warns
when pm_restore_gfp_mask() is called with saved_gfp_count == 0.

Some hibernation paths call pm_restore_gfp_mask() defensively where
the GFP mask may or may not be restricted depending on the execution
path. For example, the uswsusp interface invokes it in
SNAPSHOT_CREATE_IMAGE, SNAPSHOT_UNFREEZE, and snapshot_release().
Before the stacking change this was a silent no-op; it now triggers
a spurious WARNING.

Remove the WARN_ON() wrapper from the !saved_gfp_count check while
retaining the check itself, so that defensive calls remain harmless
without producing false warnings.

[ rjw: Subject tweak ]