CVE-2026-72191

Status: UPDATED  |  Advisory ID: CVE-2026-72191

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

ntfs3: validate split-point offset in indx_insert_into_buffer

indx_insert_into_buffer() computes

used = used1 - to_copy - sp_size;

memmove(de_t, Add2Ptr(sp, sp_size), used - le32_to_cpu(hdr1->de_off));

where sp and sp_size come from hdr_find_split(). hdr_find_split()

walks entries by le16_to_cpu(e->size) without validating that each

step stays within hdr->used or that the size field is at least

sizeof(struct NTFS_DE). index_hdr_check(), the on-load gatekeeper,

only validates header-level fields (used, total, de_off) and does

not walk per-entry sizes.

A crafted NTFS image whose leaf INDEX_HDR reports used == total but

contains one interior NTFS_DE with size = 0xFFF0 therefore passes

validation, descends to indx_insert_into_buffer() through the

ntfs_create() -> indx_insert_entry() path, and makes hdr_find_split()

return an sp whose sp_size (0xFFF0) greatly exceeds the remaining

bytes in the buffer. The u32 subtraction underflows and the memmove

count becomes a near-4-GiB value, producing an out-of-bounds kernel

write that corrupts adjacent allocations and panics the kernel.

Reproduced on 7.0.0-rc7 with UML + KASAN via a crafted image and a

single 'touch' inside the mounted directory; crash site resolves to

fs/ntfs3/index.c at the memmove. Trigger requires only local mount

of an attacker-supplied filesystem image (USB, loopback, or removable

media auto-mount).

Reject the split whenever the chosen sp plus its declared size

already extends past hdr1->used. This is the minimal fix; it

preserves the existing hdr_find_split() contract and relies on the

same out: cleanup path as the pre-existing error returns.

A prior OOB read in the very same indx_insert_into_buffer() memmove

was fixed in commit b8c44949044e ("fs/ntfs3: Fix OOB read in

indx_insert_into_buffer") by tightening hdr_find_e(), but that fix

does not cover the split-point size field path addressed here: sp is

returned by hdr_find_split(), not hdr_find_e(), and the underflow is

driven by sp->size rather than hdr->used exceeding hdr->total. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References