{"id":"CVE-2026-99063","state":"PUBLISHED","title":"dm ioctl: don't let data_start run past the buffer","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm ioctl: don't let data_start run past the buffer\n\nstruct dm_ioctl has seven bytes of trailing padding, so the smallest\nbuffer userspace is allowed to ask for, offsetof(struct dm_ioctl, data),\nis seven bytes shorter than sizeof(struct dm_ioctl).\n\nget_result_buffer() sets data_start to sizeof(struct dm_ioctl) without\nlooking at how big the buffer actually is. Ask for the minimum and\ndata_start ends up seven bytes past the end. Callers add it to\ndata_size, and ctl_ioctl() copies that much back to userspace:\n\n  BUG: KASAN: slab-out-of-bounds in _copy_to_user+0xad/0xd0\n  Read of size 312 at addr ffff8880169e4c00 by task repro-dm/140\n   ctl_ioctl+0x5e3/0xcb0\n   dm_ctl_ioctl+0x25/0x40\n  allocated 305-byte region [ffff8880169e4c00, ffff8880169e4d31)\n\nA DM_LIST_DEVICES with data_size set to 305 is enough to hit it, and the\nseven bytes that leak are whatever sat next to the allocation.\n\nClamp data_start to the buffer size.\n\nNote that this is not a security bug because the out-of-bounds read can\nonly be triggered by root.","publishedAt":"2026-10-23T12:23:04.655Z","updatedAt":"2026-10-30T12:41:27.735Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"f171054f3c4cfc4dc0cb622ec5b15793e5f23029","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"afe80ec31464f4c54cc1bc658753bc14cb14bd6c","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"98195e822343a656b92e235847ab3e72b1a3f920","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"e5c3f3d8935ecc64c962fb66e6a86dbf79218f61","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"5680b6fb3054677d4ee65d3baba24b649f1b430e","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"725b49c689bbb29ef740b0d6b5ea9390baa9a695","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"9b3fcf519d370df94a56f3b272d9eddffffa5be8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-ioctl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.25","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.25","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-ioctl.c"]}],"references":["https://git.kernel.org/stable/c/aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3","https://git.kernel.org/stable/c/f171054f3c4cfc4dc0cb622ec5b15793e5f23029","https://git.kernel.org/stable/c/afe80ec31464f4c54cc1bc658753bc14cb14bd6c","https://git.kernel.org/stable/c/98195e822343a656b92e235847ab3e72b1a3f920","https://git.kernel.org/stable/c/e5c3f3d8935ecc64c962fb66e6a86dbf79218f61","https://git.kernel.org/stable/c/5680b6fb3054677d4ee65d3baba24b649f1b430e","https://git.kernel.org/stable/c/725b49c689bbb29ef740b0d6b5ea9390baa9a695","https://git.kernel.org/stable/c/9b3fcf519d370df94a56f3b272d9eddffffa5be8"],"weaknesses":[],"ingestedAt":"2026-10-30T13:02:04.640Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99063.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99063","state":"PUBLISHED","datePublished":"2026-10-23T12:23:04.655Z","dateUpdated":"2026-10-30T12:41:27.735Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.388Z"},"containers":{"cna":{"title":"dm ioctl: don't let data_start run past the buffer","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm ioctl: don't let data_start run past the buffer\n\nstruct dm_ioctl has seven bytes of trailing padding, so the smallest\nbuffer userspace is allowed to ask for, offsetof(struct dm_ioctl, data),\nis seven bytes shorter than sizeof(struct dm_ioctl).\n\nget_result_buffer() sets data_start to sizeof(struct dm_ioctl) without\nlooking at how big the buffer actually is. Ask for the minimum and\ndata_start ends up seven bytes past the end. Callers add it to\ndata_size, and ctl_ioctl() copies that much back to userspace:\n\n  BUG: KASAN: slab-out-of-bounds in _copy_to_user+0xad/0xd0\n  Read of size 312 at addr ffff8880169e4c00 by task repro-dm/140\n   ctl_ioctl+0x5e3/0xcb0\n   dm_ctl_ioctl+0x25/0x40\n  allocated 305-byte region [ffff8880169e4c00, ffff8880169e4d31)\n\nA DM_LIST_DEVICES with data_size set to 305 is enough to hit it, and the\nseven bytes that leak are whatever sat next to the allocation.\n\nClamp data_start to the buffer size.\n\nNote that this is not a security bug because the out-of-bounds read can\nonly be triggered by root."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"f171054f3c4cfc4dc0cb622ec5b15793e5f23029","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"afe80ec31464f4c54cc1bc658753bc14cb14bd6c","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"98195e822343a656b92e235847ab3e72b1a3f920","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"e5c3f3d8935ecc64c962fb66e6a86dbf79218f61","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"5680b6fb3054677d4ee65d3baba24b649f1b430e","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"725b49c689bbb29ef740b0d6b5ea9390baa9a695","versionType":"git"},{"version":"76c072b48e39e9291fbf02d6c912cf27d65e093d","status":"affected","lessThan":"9b3fcf519d370df94a56f3b272d9eddffffa5be8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-ioctl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.25","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.25","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-ioctl.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3"},{"url":"https://git.kernel.org/stable/c/f171054f3c4cfc4dc0cb622ec5b15793e5f23029"},{"url":"https://git.kernel.org/stable/c/afe80ec31464f4c54cc1bc658753bc14cb14bd6c"},{"url":"https://git.kernel.org/stable/c/98195e822343a656b92e235847ab3e72b1a3f920"},{"url":"https://git.kernel.org/stable/c/e5c3f3d8935ecc64c962fb66e6a86dbf79218f61"},{"url":"https://git.kernel.org/stable/c/5680b6fb3054677d4ee65d3baba24b649f1b430e"},{"url":"https://git.kernel.org/stable/c/725b49c689bbb29ef740b0d6b5ea9390baa9a695"},{"url":"https://git.kernel.org/stable/c/9b3fcf519d370df94a56f3b272d9eddffffa5be8"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:41:27.735Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.12.113"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"7.2.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}