Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: ntfs: validate usa_ofs before preserving the update sequence number When ntfs_mft_record_alloc() reuses a free mft record it reads the old update sequence number straight from the on-disk record: usn = *(__le16 *)((u8 *)m + le16_to_cpu(m->usa_ofs)); Here m points into the raw $MFT page-cache folio, which still holds unvalidated, MST-protected bytes: the folio is read by a plain iomap_read_folio() and neither post_read_mst_fixup() nor ntfs_mft_record_check() has run on it (both work on private copies). m->usa_ofs is therefore an untrusted u16, and a corrupted record can put it past the end of the record so the two-byte read lands outside the folio. Reading such a record while creating a file gives, under KASAN: BUG: KASAN: use-after-free in ntfs_mft_record_alloc+... Read of size 2 at addr ... ntfs_mft_record_alloc -> __ntfs_create -> ntfs_create -> path_openat Only preserve the old update sequence number when usa_ofs is even and in range, mirroring the check ntfs_mft_record_check() already applies; otherwise leave usn zero, which the existing restore below skips.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 495e90fa334828d4119061e2726af51d0a0fb4ed before ea5a3c30710710c1dc5e483d3313309ec2e868f7; affected 495e90fa334828d4119061e2726af51d0a0fb4ed before 81684340963da2e898eabb8c1e274433d9375bc6 |
| Linux / Linux | affected 7.1; unaffected 0 before 7.1; unaffected 7.2.6 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.