{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89436","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.702Z","datePublished":"2026-09-11T19:43:06.732Z","dateUpdated":"2026-09-13T06:29:20.944Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:29:20.944Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[]\n\nacpi_pcc_retrieve_biosdata() rejects SINF packages only when\npcc->num_sifr is strictly less than hkey->package.count, then\nunconditionally writes a trailing sentinel at\npcc->sinf[hkey->package.count]. But pcc->sinf[] is allocated with\nexactly pcc->num_sifr elements (valid indices 0..num_sifr-1), so that\nwrite needs num_sifr strictly greater than package.count to stay in\nbounds -- num_sifr == package.count passes the existing check but\nstill overflows by one element.\n\nThis is exactly the case probe()'s existing num_sifr++ workaround\n(\"Some DSDT-s have an off-by-one bug where the SINF package count is\none higher than the SQTY reported value\") is written to accommodate:\nwhen a DSDT's SINF package count equals SQTY+1, the workaround makes\nnum_sifr equal to package.count, which is precisely the boundary that\noverflows here. Found via UBSan (array-index-out-of-bounds) on\nhardware where HKEY.SQTY returns 37 and HKEY.SINF()'s package has 38\nelements: num_sifr becomes 38 after the += 1 workaround, the loop\ncorrectly fills indices 0..37, and the sentinel write then targets\nindex 38, one past the end -- a silent 4-byte heap overflow on kernels\nwithout CONFIG_UBSAN.\n\nTightening the rejection check to num_sifr <= package.count would\navoid the overflow but breaks probe() entirely on exactly this\nhardware, since num_sifr == package.count is the case the off-by-one\nworkaround exists to support. Nothing else in the driver reads this\nsentinel value back, so simply skip the write when there is no room\nfor it instead."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The overflow is reached by reading world-readable sysfs files under /sys/bus/acpi/devices/MAT00xx:00/ (numbatt, lcdtype, mute, sticky_key, eco_mode, brightness) and /sys/class/backlight/panasonic/, which call acpi_pcc_retrieve_biosdata(); there is no network or remote-peer path into this ACPI laptop driver.\nAC:L - On Panasonic Let's Note firmware where HKEY.SINF's package count equals SQTY+1, every sysfs or backlight read deterministically writes the sentinel one past pcc->sinf[]; no race is required. That DSDT off-by-one is a fixed property of the affected hardware being scored, not a per-attempt condition.\nPR:L - The triggering attributes are DEVICE_ATTR_RO (0444) or DEVICE_ATTR_RW (0644), so any unprivileged local user can read them and cause the out-of-bounds write with no capability, group membership, or init-namespace root.\nUI:N - The attacker reads a sysfs attribute from their own process; no victim action such as mounting a filesystem, plugging hardware, or confirming a prompt is required.\nS:U - The 4-byte heap overflow corrupts host kernel slab memory belonging to the same kernel security authority that hosts the driver; it does not cross a VM, IOMMU, or sandbox boundary.\nC:H - The off-by-one writes 0xffffffff one u32 past the kzalloc_flex pcc_acpi object, corrupting adjacent kmalloc slab contents including pointers on size-class-aligned allocations; that heap corruption can be leveraged for kernel information disclosure, so confidentiality is High.\nI:H - This is a repeatable 4-byte out-of-bounds heap write of the sentinel past pcc->sinf[]. Per kernel scoring guidance an OOB write is High because heap grooming can place a security-relevant object at the overwritten offset and turn it into a control-flow or privilege primitive.\nA:H - Writing past the kmalloc object can corrupt neighboring slab objects or metadata and produce a kernel oops or panic, and debug kernels trip KASAN/UBSAN on the counted-by overflow; any such crash is Availability High."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/platform/x86/panasonic-laptop.c"],"versions":[{"version":"a3d0dbd18ce908292607bb6cf37c978ece8a33d4","lessThan":"a93df956ee4d903735b6d395362c839cb1dc07e3","status":"affected","versionType":"git"},{"version":"a3d0dbd18ce908292607bb6cf37c978ece8a33d4","lessThan":"329f10d8be193bf36af124e00b9dd6644cd71724","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/platform/x86/panasonic-laptop.c"],"versions":[{"version":"7.2","status":"affected"},{"version":"0","lessThan":"7.2","status":"unaffected","versionType":"semver"},{"version":"7.2.4","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.2","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.2","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/a93df956ee4d903735b6d395362c839cb1dc07e3"},{"url":"https://git.kernel.org/stable/c/329f10d8be193bf36af124e00b9dd6644cd71724"}],"title":"platform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[]","x_generator":{"engine":"bippy-1.2.0"}}}}