{"id":"CVE-2026-64186","state":"PUBLISHED","title":"iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Remove latent out-of-bounds access in IOMMU debugfs\n\nIn iommu_mmio_write() and iommu_capability_write(), the variables\ndbg_mmio_offset and dbg_cap_offset are declared as int. However, they\nare populated using kstrtou32_from_user(). If a user provides a\nsufficiently large value, it can become a negative integer.\n\nPrior to this patch, the AMD IOMMU debugfs implementation was already\nprotected by different mechanisms.\n\n1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so\n   e.g. 0xffffffff isn't a valid input.\n\n  if (cnt > OFS_IN_SZ)\n     return -EINVAL;\n\n2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int\n   and iommu->mmio_phys_end is u64\n\n  if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64))\n      return -EINVAL;\n\n3. The show handlers would currently catch the negative number and\n   refuse to perform the read.\n\nReplace kstrtou32_from_user() with kstrtos32_from_user() to parse the\ninput, and check for negative values to explicitly prevent out-of-bounds\nmemory accesses directly in iommu_mmio_write() and\niommu_capability_write().","publishedAt":"2026-07-19T15:41:08.054Z","updatedAt":"2026-07-19T15:41:08.054Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7a4ee419e8c144b747a8915856e91a034d7c8f34","status":"affected","lessThan":"488d2c76bd9f78433a70690d1054bfae3d39a407","versionType":"git"},{"version":"7a4ee419e8c144b747a8915856e91a034d7c8f34","status":"affected","lessThan":"62f9dfbf1aceae88b03c5ca08f7d36e943939dec","versionType":"git"},{"version":"7a4ee419e8c144b747a8915856e91a034d7c8f34","status":"affected","lessThan":"8dfd3d8d74435344ee8dc9237596959c8b2a6cbe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/amd/debugfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/amd/debugfs.c"]}],"references":["https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407","https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec","https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64186.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64186","state":"PUBLISHED","datePublished":"2026-07-19T15:41:08.054Z","dateUpdated":"2026-07-19T15:41:08.054Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.039Z"},"containers":{"cna":{"title":"iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Remove latent out-of-bounds access in IOMMU debugfs\n\nIn iommu_mmio_write() and iommu_capability_write(), the variables\ndbg_mmio_offset and dbg_cap_offset are declared as int. However, they\nare populated using kstrtou32_from_user(). If a user provides a\nsufficiently large value, it can become a negative integer.\n\nPrior to this patch, the AMD IOMMU debugfs implementation was already\nprotected by different mechanisms.\n\n1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so\n   e.g. 0xffffffff isn't a valid input.\n\n  if (cnt > OFS_IN_SZ)\n     return -EINVAL;\n\n2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int\n   and iommu->mmio_phys_end is u64\n\n  if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64))\n      return -EINVAL;\n\n3. The show handlers would currently catch the negative number and\n   refuse to perform the read.\n\nReplace kstrtou32_from_user() with kstrtos32_from_user() to parse the\ninput, and check for negative values to explicitly prevent out-of-bounds\nmemory accesses directly in iommu_mmio_write() and\niommu_capability_write()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"7a4ee419e8c144b747a8915856e91a034d7c8f34","status":"affected","lessThan":"488d2c76bd9f78433a70690d1054bfae3d39a407","versionType":"git"},{"version":"7a4ee419e8c144b747a8915856e91a034d7c8f34","status":"affected","lessThan":"62f9dfbf1aceae88b03c5ca08f7d36e943939dec","versionType":"git"},{"version":"7a4ee419e8c144b747a8915856e91a034d7c8f34","status":"affected","lessThan":"8dfd3d8d74435344ee8dc9237596959c8b2a6cbe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/amd/debugfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/iommu/amd/debugfs.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407"},{"url":"https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec"},{"url":"https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-07-19T15:41:08.054Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}