High · published August 15, 2026
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: add bounds check to run_get_highest_vcn()
run_get_highest_vcn() parses a packed NTFS mapping-pairs buffer without
any length bound, relying solely on a 0x00 terminator to stop. A
crafted $LogFile UpdateMappingPairs record whose embedded attribute
contains mapping-pairs runs without a terminator causes the function to
read past the slab allocation, triggering a KASAN slab-out-of-bounds
read on mount.
The sibling function run_unpack() received an analogous bounds-check in
commit b62567bca474 ("ntfs3: add buffer boundary checks to run_unpack()"),
but run_get_highest_vcn() was missed.
Take a run_buf_size parameter and reject any run header whose payload
would extend past the buffer end, mirroring the pattern used by
run_unpack(). The caller in fslog.c passes the remaining attribute
bytes after the mapping-pairs offset.
KASAN report (on mainline v7.1 merge window HEAD):
BUG: KASAN: slab-out-of-bounds in run_get_highest_vcn+0x3c0/0x410
Read of size 1 at addr ffff88800e2d5400 by task mount/72
Call Trace:
run_get_highest_vcn+0x3c0/0x410
do_action.isra.0+0x3ba8/0x7b50
log_replay+0x9ddd/0x10200
ntfs_loadlog_and_replay+0x4ad/0x610
ntfs_fill_super+0x214a/0x4540