Bug 2466979 (CVE-2026-43075) - CVE-2026-43075 kernel: ocfs2: fix out-of-bounds write in ocfs2_write_end_inline
Summary: CVE-2026-43075 kernel: ocfs2: fix out-of-bounds write in ocfs2_write_end_inline
Keywords:
Status: NEW
Alias: CVE-2026-43075
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
unspecified
unspecified
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-05-06 10:01 UTC by OSIDB Bzimport
Modified: 2026-05-06 15:30 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-05-06 10:01:37 UTC
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.


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