High · published August 15, 2026
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: bound attr_off in UpdateResidentValue against data_off
In do_action()'s UpdateResidentValue case (fslog.c:3307),
lrh->attr_off and lrh->redo_len come from the on-disk LRH.
When they satisfy aoff + dlen < attr->res.data_off, the
assignment
attr->res.data_size = cpu_to_le32(aoff + dlen - data_off);
underflows to ~4 GiB (e.g. 0xFFFFFFF9 when aoff=0x10, dlen=1,
data_off=0x18). Subsequent code that reads attr->res.data_size
to walk the resident attribute payload would then read up to
4 GiB past the 1024-byte MFT record allocation.
The existing mi_enum_attr() defense in fs/ntfs3/record.c:287
catches the corrupted data_size on the next attribute walk
and fails the mount, but only on the path that walks all
attributes. A read site that picks an attribute by name and
reads its data_size without re-validating is not covered.
Validate aoff against data_off and asize at the source.
Reproduced under UML+KASAN on mainline 8d90b09e6741 via
pr_warn-only probe: with aoff=0x10 and data_off=0x18, the
post-assignment data_size is 0xfffffff9 (mount then fails
at -22 from mi_enum_attr).
[[email protected]: clang-formatted the changes]