hwmon: (pwm-fan) Stop RPM timer before freeing tach data

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98198
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 09:18:05 UTC
Updated2026-10-21 13:21:25 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: hwmon: (pwm-fan) Stop RPM timer before freeing tach data sample_timer() rearms the RPM timer and accesses the devm-managed ctx->tachs and ctx->pulses_per_revolution arrays. The cleanup action which stops the timer is registered before those arrays are allocated. Since devres releases entries in reverse order, driver detach can free the arrays before pwm_fan_cleanup() shuts down the timer. A timer expiry in that window accesses the freed tach data. With a KASAN kernel, a test-only kprobe delayed entry to pwm_fan_cleanup() while normal sysfs unbind ran. Each of three runs reported three four-byte reads and two four-byte writes in sample_timer() after its backing devm allocations had been freed. The helper did not invoke the timer callback, cleanup actions or free functions. With the fix, three matching unbind runs completed without KASAN, BUG, WARNING, Oops or panic. Instrumentation confirmed that timer retirement completed before the first timer backing allocation was released. Split timer retirement from the power cleanup and register its devres action after the timer backing data and IRQ actions are installed. This preserves the early power rollback action while ensuring the timer is retired before its backing data is released. Use timer_shutdown_sync() because the callback can rearm itself.

Risk And Classification

EPSS: 0.001750000 probability, percentile 0.066730000 (date 2026-10-21)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 01695410d4529e38fea6159fa9f1260c598290b0 d073d306e587c1f35aaf9c07c42e54a3d5895d8f git Not specified
CNA Linux Linux affected 01695410d4529e38fea6159fa9f1260c598290b0 1e824fdb14a187ce56697e803b02b1e86243a755 git Not specified
CNA Linux Linux affected 01695410d4529e38fea6159fa9f1260c598290b0 a5ce3fe5335a24d0220958c6866830a6d5fa1cc0 git Not specified
CNA Linux Linux affected 01695410d4529e38fea6159fa9f1260c598290b0 b48339b0a577783e4590a69e4cd2f2760ce33154 git Not specified
CNA Linux Linux affected 01695410d4529e38fea6159fa9f1260c598290b0 26d5ff79768548efb1e604bb6e8697c101e06269 git Not specified
CNA Linux Linux affected 5.12 Not specified
CNA Linux Linux unaffected 5.12 semver Not specified
CNA Linux Linux unaffected 6.6.160 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.112 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.54 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.8 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/1e824fdb14a187ce56697e803b02b1e86243a755 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d073d306e587c1f35aaf9c07c42e54a3d5895d8f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a5ce3fe5335a24d0220958c6866830a6d5fa1cc0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/26d5ff79768548efb1e604bb6e8697c101e06269 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b48339b0a577783e4590a69e4cd2f2760ce33154 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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