{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89722","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.759Z","datePublished":"2026-09-11T19:46:34.427Z","dateUpdated":"2026-09-13T06:24:09.318Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:24:09.318Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nPCI/sysfs: Fix out-of-bounds read in pci_write_legacy_io()\n\npci_write_legacy_io() loads 4 bytes from the kernfs write buffer\nregardless of how many bytes userspace wrote:\n\n  if (count != 1 && count != 2 && count != 4)\n          return -EINVAL;\n\n  return pci_legacy_write(bus, off, *(u32 *)buf, count);\n\nkernfs_fop_write_iter() allocates the buffer with kmalloc(len + 1),\nso a 1-byte write to the legacy_io sysfs file allocates 2 bytes and\nthe unconditional u32 load reads up to 2 bytes past the end of the\nallocation, which KASAN reports as a slab-out-of-bounds read.\nSimilarly, a 2-byte write overreads by 1 byte.\n\nThus, read only the number of bytes requested using get_unaligned_le16()\nand get_unaligned_le32() for the 2 and 4 byte cases, interpreting the\nbuffer as little-endian to match the byte ordering of PCI I/O port\nspace.\n\nThe PowerPC implementation previously compensated for the generic\ncode's native-endian 32-bit load by shifting the value into place\nfor the 1 and 2 byte cases.  The shifts were only correct on\nbig-endian kernels.\n\nOn little-endian PowerPC (POWER8 and later), they extracted the wrong\nbytes, so a 1-byte write wrote an out-of-bounds byte instead of the\nrequested value.  On big-endian, the native load also caused out_le16()\nand out_le32() to reverse the user's bytes on the wire for 2 and 4 byte\nwrites.  The little-endian helpers resolve both issues, so the shifts\nare removed.\n\nNo changes are needed for the Alpha platform.\n\nThe legacy_io file is root-only and exists only on Alpha and PowerPC,\nthe two architectures that define HAVE_PCI_LEGACY."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/powerpc/kernel/pci-common.c","drivers/pci/pci-sysfs.c"],"versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"e892f05f1f790d5721cd8e3c561ed76da7e08bae","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"7a99e9c7011905734cc2739038f2a224b6be0d1f","status":"affected","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"dc76258d0132df1d831a5a29758bd448ca9c566e","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/powerpc/kernel/pci-common.c","drivers/pci/pci-sysfs.c"],"versions":[{"version":"2.6.12","status":"affected"},{"version":"0","lessThan":"2.6.12","status":"unaffected","versionType":"semver"},{"version":"6.18.50","lessThanOrEqual":"6.18.*","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":"2.6.12","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/e892f05f1f790d5721cd8e3c561ed76da7e08bae"},{"url":"https://git.kernel.org/stable/c/7a99e9c7011905734cc2739038f2a224b6be0d1f"},{"url":"https://git.kernel.org/stable/c/dc76258d0132df1d831a5a29758bd448ca9c566e"}],"title":"PCI/sysfs: Fix out-of-bounds read in pci_write_legacy_io()","x_generator":{"engine":"bippy-1.2.0"}}}}