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.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://git.kernel.org/stable/c/0c1af902223b6fcedb60904ca0b551254686c7b9
• https://git.kernel.org/stable/c/69d3c69ade1e4285ab4ca48fe7acee0767e65604
• https://git.kernel.org/stable/c/7bc5da4842bed3252d26e742213741a4d0ac1b14
• https://git.kernel.org/stable/c/947f953978b0d9463498d548d0f054f5a75be2e9
• https://git.kernel.org/stable/c/e2c9dc6b6e96f3585f2a1062ca3374a52db0938f
• https://www.suse.com/security/cve/CVE-2026-43075.html
• https://security-tracker.debian.org/tracker/CVE-2026-43075

CWEs

CWE-787