Bug 2525464 (CVE-2026-80638)

Summary: CVE-2026-80638 kernel: ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the ocfs2 component of the Linux kernel. When a user unlinks a refcounted file whose refcount tree has leaf blocks, an out-of-bounds write occurs within the ocfs2_remove_refcount_extent() function. This happens because a memset operation writes past the intended memory boundary due to an incorrect size calculation. A successful exploit of this vulnerability can lead to a system crash, resulting in a denial of service (DoS).
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Description OSIDB Bzimport 2026-08-28 07:46:19 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent

[BUG]
Unlinking a refcounted file whose refcount tree has leaf blocks
triggers a fortify panic due to an out-of-bounds write.

[CAUSE]
When the last leaf block is removed from a refcount tree,
ocfs2_remove_refcount_extent() converts the root back to leaf mode
with a bulk memset on &rb->rf_records. rf_records sits in an anonymous
union with rf_list. rf_list.l_tree_depth aliases rf_records.rl_count,
and is 0 for a single-level tree. With rl_count equal to 0, the memset
writes past the 16-byte declared size of rf_records, which the fortify
checker catches.

[FIX]
Replace the bulk memset on &rb->rf_records with a correctly-bounded
memset on rl_recs[] alone, after setting rl_count to the correct value.
Comment 1 gkamathe 2026-09-01 06:46:47 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082840-CVE-2026-80638-fbf1@gregkh/T