CVE-2026-80672
Description
In the Linux kernel, the following vulnerability has been resolved:
ntfs: fix u16 truncation of restart-area length check
ntfs_check_restart_area() validates that the $LogFile restart area and
its trailing log client record array fit within the system page size:
u16 ra_ofs, ra_len, ca_ofs;
...
ra_len = ca_ofs + le16_to_cpu(ra->log_clients) *
sizeof(struct log_client_record);
if (ra_ofs + ra_len > le32_to_cpu(rp->system_page_size) || ...)
return false;
ra_len is u16, but the right-hand side is computed in size_t
(sizeof(struct log_client_record) == 160). Both ca_ofs and log_clients
come straight from the on-disk restart area. With an on-disk
log_clients of 410 the product 410 * 160 = 65600; adding ca_ofs and
storing into the u16 ra_len truncates modulo 65536 (e.g. ca_ofs 64
gives ra_len 128), so the 'fits in the page' check passes even though
the client array described by log_clients extends far beyond the page.
ntfs_check_log_client_array() then walks the array bounded only by the
on-disk log_clients count:
cr = ca + idx;
if (cr->prev_client != LOGFILE_NO_CLIENT) ...
For log_clients 410 it dereferences records up to ca + 409 * 160,
~64 KiB past the kvzalloc(system_page_size) restart-page buffer -- an
out-of-bounds read of attacker-controlled extent, reachable when a
crafted NTFS image is mounted (load_and_check_logfile() at mount time).
This is the in-kernel analogue of CVE-2022-30789, fixed in the ntfs-3g
userspace driver but never in this revived classic driver.
Compute the restart-area length in a u32 so the existing bounds check
rejects an over-large client array instead of being defeated by the
truncation. Widen ra_ofs and ca_ofs to u32 as well: both are loaded
from __le16 on-disk fields and every comparison already promotes to
int/size_t, so this changes no result and keeps the declaration uniform.