High · published October 28, 2025
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: reject index allocation if $BITMAP is empty but blocks exist
Index allocation requires at least one bit in the $BITMAP attribute to
track usage of index entries. If the bitmap is empty while index blocks
are already present, this reflects on-disk corruption.
syzbot triggered this condition using a malformed NTFS image. During a
rename() operation involving a long filename (which spans multiple
index entries), the empty bitmap allowed the name to be added without
valid tracking. Subsequent deletion of the original entry failed with
-ENOENT, due to unexpected index state.
Reject such cases by verifying that the bitmap is not empty when index
blocks exist.