{"id":"CVE-2026-99063","summary":"dm ioctl: don't let data_start run past the buffer","details":"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.","modified":"2026-11-01T02:31:47.998633951Z","published":"2026-10-23T12:23:04.655Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99063.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/5680b6fb3054677d4ee65d3baba24b649f1b430e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/725b49c689bbb29ef740b0d6b5ea9390baa9a695"},{"type":"WEB","url":"https://git.kernel.org/stable/c/98195e822343a656b92e235847ab3e72b1a3f920"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9b3fcf519d370df94a56f3b272d9eddffffa5be8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/afe80ec31464f4c54cc1bc658753bc14cb14bd6c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e5c3f3d8935ecc64c962fb66e6a86dbf79218f61"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f171054f3c4cfc4dc0cb622ec5b15793e5f23029"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99063.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99063"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"76c072b48e39e9291fbf02d6c912cf27d65e093d"},{"fixed":"aaa93e41ae308ad9ff9d9ba3296a0d0f4d45bad3"},{"fixed":"f171054f3c4cfc4dc0cb622ec5b15793e5f23029"},{"fixed":"afe80ec31464f4c54cc1bc658753bc14cb14bd6c"},{"fixed":"98195e822343a656b92e235847ab3e72b1a3f920"},{"fixed":"e5c3f3d8935ecc64c962fb66e6a86dbf79218f61"},{"fixed":"5680b6fb3054677d4ee65d3baba24b649f1b430e"},{"fixed":"725b49c689bbb29ef740b0d6b5ea9390baa9a695"},{"fixed":"9b3fcf519d370df94a56f3b272d9eddffffa5be8"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99063.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.25"},{"fixed":"5.10.273"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.224"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.191"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.160"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.113"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.57"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99063.json"}}],"schema_version":"1.9.2"}