CVE-2026-43075
Description
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: fix out-of-bounds write in ocfs2_write_end_inline
KASAN reports a use-after-free write of 4086 bytes in
ocfs2_write_end_inline, called from ocfs2_write_end_nolock during a
copy_file_range splice fallback on a corrupted ocfs2 filesystem mounted on
a loop device. The actual bug is an out-of-bounds write past the inode
block buffer, not a true use-after-free. The write overflows into an
adjacent freed page, which KASAN reports as UAF.
The root cause is that ocfs2_try_to_write_inline_data trusts the on-disk
id_count field to determine whether a write fits in inline data. On a
corrupted filesystem, id_count can exceed the physical maximum inline data
capacity, causing writes to overflow the inode block buffer.
Call trace (crash path):
vfs_copy_file_range (fs/read_write.c:1634)
do_splice_direct
splice_direct_to_actor
iter_file_splice_write
ocfs2_file_write_iter
generic_perform_write
ocfs2_write_end
ocfs2_write_end_nolock (fs/ocfs2/aops.c:1949)
ocfs2_write_end_inline (fs/ocfs2/aops.c:1915)
memcpy_from_folio <-- KASAN: write OOB
So add id_count upper bound check in ocfs2_validate_inode_block() to
alongside the existing i_size check to fix it.