CVE-2026-72192

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

ntfs3: bound tomove in indxinsertintoroot before hdrinserthead

indxinsertintoroot() promotes a full resident $INDEXROOT into

$INDEX_ALLOCATION and copies all non-last resident root entries into

a newly allocated INDEXBUFFER via hdrinsert_head(). The source

byte count 'to_move' is summed from the on-disk resident entry sizes

and is independent of the destination buffer size, which comes from

root->indexblocksize (via indx->index_bits).

A crafted NTFS image that keeps a valid, full resident root but

shrinks root->indexblocksize down to 512 after the root has been

populated makes hdrinserthead() memcpy attacker-controlled resident

entry bytes past the end of the kmalloc(1u << indx->index_bits)

allocation returned by indx_new(). For a 512-byte destination and a

resident root whose non-last entries total 560 bytes, the memcpy

overruns by 120 bytes and a following memmove extends the highest

written offset to 136 bytes past the allocation. The overflow bytes

are a direct copy of on-disk entries (via kmemdup), so they are

fully attacker-controlled.

The write is reachable from unprivileged open(O_CREAT) on a mounted

crafted NTFS image: a single sufficiently long create in a directory

whose resident root is already full forces root promotion and

triggers the copy.

This is a controlled out-of-bounds write of 120-136 bytes past a

kmalloc(indexblocksize) allocation, with attacker-controlled

content. It is a bounded adjacent-heap corruption primitive; it is

not an arbitrary-address write. Successful exploitation into a named

victim object depends on the surrounding slab layout.

Reject the copy at the sink. The destination's INDEX_HDR already

reports hdr_total (the payload capacity of the new buffer) and

hdr_used (the bytes already consumed by the terminal END entry

installed by indxnew()); require that tomove fits in the remaining

payload before calling hdrinserthead(). On mismatch, fail with

-EINVAL and mark the filesystem as having a detected on-disk

inconsistency, which is the same behaviour as the surrounding

validation in this function.