platform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[]

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89436
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:23 UTC
Updated2026-09-11 20:19:23 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: platform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[] acpi_pcc_retrieve_biosdata() rejects SINF packages only when pcc->num_sifr is strictly less than hkey->package.count, then unconditionally writes a trailing sentinel at pcc->sinf[hkey->package.count]. But pcc->sinf[] is allocated with exactly pcc->num_sifr elements (valid indices 0..num_sifr-1), so that write needs num_sifr strictly greater than package.count to stay in bounds -- num_sifr == package.count passes the existing check but still overflows by one element. This is exactly the case probe()'s existing num_sifr++ workaround ("Some DSDT-s have an off-by-one bug where the SINF package count is one higher than the SQTY reported value") is written to accommodate: when a DSDT's SINF package count equals SQTY+1, the workaround makes num_sifr equal to package.count, which is precisely the boundary that overflows here. Found via UBSan (array-index-out-of-bounds) on hardware where HKEY.SQTY returns 37 and HKEY.SINF()'s package has 38 elements: num_sifr becomes 38 after the += 1 workaround, the loop correctly fills indices 0..37, and the sentinel write then targets index 38, one past the end -- a silent 4-byte heap overflow on kernels without CONFIG_UBSAN. Tightening the rejection check to num_sifr <= package.count would avoid the overflow but breaks probe() entirely on exactly this hardware, since num_sifr == package.count is the case the off-by-one workaround exists to support. Nothing else in the driver reads this sentinel value back, so simply skip the write when there is no room for it instead.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a3d0dbd18ce908292607bb6cf37c978ece8a33d4 a93df956ee4d903735b6d395362c839cb1dc07e3 git Not specified
CNA Linux Linux affected a3d0dbd18ce908292607bb6cf37c978ece8a33d4 329f10d8be193bf36af124e00b9dd6644cd71724 git Not specified
CNA Linux Linux affected 7.2 Not specified
CNA Linux Linux unaffected 7.2 semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a93df956ee4d903735b6d395362c839cb1dc07e3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/329f10d8be193bf36af124e00b9dd6644cd71724 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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