Bug 2466999 (CVE-2026-43076)

Summary: CVE-2026-43076 kernel: ocfs2: validate inline data i_size during inode read
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the ocfs2 filesystem module of the Linux kernel. This vulnerability occurs when the system attempts to read an inode from a corrupted filesystem, where the inline data size is not properly validated. This can lead to a use-after-free condition, potentially allowing a local attacker to cause a system crash (Denial of Service) or, in some cases, execute arbitrary code.
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Description OSIDB Bzimport 2026-05-06 10:02:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ocfs2: validate inline data i_size during inode read

When reading an inode from disk, ocfs2_validate_inode_block() performs
various sanity checks but does not validate the size of inline data.  If
the filesystem is corrupted, an inode's i_size can exceed the actual
inline data capacity (id_count).

This causes ocfs2_dir_foreach_blk_id() to iterate beyond the inline data
buffer, triggering a use-after-free when accessing directory entries from
freed memory.

In the syzbot report:
  - i_size was 1099511627576 bytes (~1TB)
  - Actual inline data capacity (id_count) is typically <256 bytes
  - A garbage rec_len (54648) caused ctx->pos to jump out of bounds
  - This triggered a UAF in ocfs2_check_dir_entry()

Fix by adding a validation check in ocfs2_validate_inode_block() to ensure
inodes with inline data have i_size <= id_count.  This catches the
corruption early during inode read and prevents all downstream code from
operating on invalid data.
Comment 1 Alexander B 2026-05-06 14:31:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050612-CVE-2026-43076-f173@gregkh/T