Bug 2516931 (CVE-2026-74349)

Summary: CVE-2026-74349 kernel: ocfs2: reject FITRIM ranges shorter than a cluster
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
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 Linux kernel's OCFS2 (Oracle Cluster File System version 2) component. A local attacker with appropriate permissions could trigger an issue during filesystem trimming operations. By providing a specific range for trimming that is smaller than expected, an internal calculation error (integer underflow) occurs. This error could cause the system to trim data outside the intended area, potentially leading to data corruption or making the system unavailable (Denial of Service).
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Description OSIDB Bzimport 2026-08-15 06:41:03 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ocfs2: reject FITRIM ranges shorter than a cluster

ocfs2_trim_mainbm() trims the global bitmap in cluster units, but its
too-short range validation only checks sb->s_blocksize.

On filesystems with a cluster size larger than the block size, a FITRIM
range that is at least one block but shorter than one cluster is accepted
and shifted down to len == 0.  The later start + len - 1 and len -= ... 
arithmetic then underflows and can drive trimming past the requested
range.

Reject ranges shorter than s_clustersize instead.  That preserves the
existing -EINVAL behavior for requests that cannot discard even one
allocation unit and keeps zero-cluster trims out of the group walk.
Comment 1 Keith Grant 2026-08-20 18:36:33 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081559-CVE-2026-74349-d8b3@gregkh/T