CVE-2026-72192

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

ntfs3: bound to_move in indx_insert_into_root before hdr_insert_head

indx_insert_into_root() promotes a full resident $INDEX_ROOT into $INDEX_ALLOCATION and copies all non-last resident root entries into a newly allocated INDEX_BUFFER via hdr_insert_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->index_block_size (via indx->index_bits).

A crafted NTFS image that keeps a valid, full resident root but shrinks root->index_block_size down to 512 after the root has been populated makes hdr_insert_head() 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(index_block_size) 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 destinations 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 indx_new()); require that to_move fits in the remaining payload before calling hdr_insert_head(). 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.

Affected Software

References

• https://git.kernel.org/stable/c/0af83b8155cc848e9f5d2c36e20a70d024214649
• https://git.kernel.org/stable/c/194b00c99ba971fa7cf6acd747a36032c6de54eb
• https://git.kernel.org/stable/c/53c5f3b2da3774b41534728aba295c098c9efa19
• https://git.kernel.org/stable/c/9b6926ac9c970ae0b2c2fe6289b16e9aa10b6a67
• https://git.kernel.org/stable/c/aaa1f956c0fc41089a4a534da7df91552a08a47c
• https://git.kernel.org/stable/c/cb3161deebcaf8d36d3115abf452c633f2180fc1
• https://git.kernel.org/stable/c/d240f5f9d036b8180224954d9873f172b6be4dd8