{"id":"CVE-2026-72191","summary":"ntfs3: validate split-point offset in indx_insert_into_buffer","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nntfs3: validate split-point offset in indx_insert_into_buffer\n\nindx_insert_into_buffer() computes\n\n    used = used1 - to_copy - sp_size;\n    memmove(de_t, Add2Ptr(sp, sp_size), used - le32_to_cpu(hdr1-\u003ede_off));\n\nwhere sp and sp_size come from hdr_find_split().  hdr_find_split()\nwalks entries by le16_to_cpu(e-\u003esize) without validating that each\nstep stays within hdr-\u003eused or that the size field is at least\nsizeof(struct NTFS_DE).  index_hdr_check(), the on-load gatekeeper,\nonly validates header-level fields (used, total, de_off) and does\nnot walk per-entry sizes.\n\nA crafted NTFS image whose leaf INDEX_HDR reports used == total but\ncontains one interior NTFS_DE with size = 0xFFF0 therefore passes\nvalidation, descends to indx_insert_into_buffer() through the\nntfs_create() -\u003e indx_insert_entry() path, and makes hdr_find_split()\nreturn an sp whose sp_size (0xFFF0) greatly exceeds the remaining\nbytes in the buffer.  The u32 subtraction underflows and the memmove\ncount becomes a near-4-GiB value, producing an out-of-bounds kernel\nwrite that corrupts adjacent allocations and panics the kernel.\n\nReproduced on 7.0.0-rc7 with UML + KASAN via a crafted image and a\nsingle 'touch' inside the mounted directory; crash site resolves to\nfs/ntfs3/index.c at the memmove.  Trigger requires only local mount\nof an attacker-supplied filesystem image (USB, loopback, or removable\nmedia auto-mount).\n\nReject the split whenever the chosen sp plus its declared size\nalready extends past hdr1-\u003eused.  This is the minimal fix; it\npreserves the existing hdr_find_split() contract and relies on the\nsame out: cleanup path as the pre-existing error returns.\n\nA prior OOB read in the very same indx_insert_into_buffer() memmove\nwas fixed in commit b8c44949044e (\"fs/ntfs3: Fix OOB read in\nindx_insert_into_buffer\") by tightening hdr_find_e(), but that fix\ndoes not cover the split-point size field path addressed here: sp is\nreturned by hdr_find_split(), not hdr_find_e(), and the underflow is\ndriven by sp-\u003esize rather than hdr-\u003eused exceeding hdr-\u003etotal.","modified":"2026-08-25T03:51:45.159529103Z","published":"2026-08-15T05:53:51.893Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72191.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1758a564b6ebe7f4a82f23c9851d1cae15549457"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4c2f648139a0a86f4486170f72e24fedd4fae74e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7bf74e6baf810fe325f111996496c678fc6e244f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8e4ba5a38c155bb3c1c11e63cd285b178cdb099e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b232eb5c9fe11ec2368e9b565db69c724c35fbd2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f1df9d771df47aa40de6d70949c28720ae1e430d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f3624cc069195001c88df7a291af215f2133ff2c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72191.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72191"},{"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":"82cae269cfa953032fbb8980a7d554d60fb00b17"},{"fixed":"8e4ba5a38c155bb3c1c11e63cd285b178cdb099e"},{"fixed":"4c2f648139a0a86f4486170f72e24fedd4fae74e"},{"fixed":"b232eb5c9fe11ec2368e9b565db69c724c35fbd2"},{"fixed":"7bf74e6baf810fe325f111996496c678fc6e244f"},{"fixed":"f3624cc069195001c88df7a291af215f2133ff2c"},{"fixed":"1758a564b6ebe7f4a82f23c9851d1cae15549457"},{"fixed":"f1df9d771df47aa40de6d70949c28720ae1e430d"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72191.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.15.0"},{"fixed":"5.15.217"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.184"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72191.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}