Bug 2516425 (CVE-2026-72438)

Summary: CVE-2026-72438 kernel: md/raid10: fix writes_pending and barrier reference leaks on discard failures
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
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 Linux kernel's multiple device (MD) driver, specifically in the RAID10 implementation. This vulnerability occurs due to reference leaks in the `writes_pending` and `barrier` mechanisms during discard failures. An attacker could potentially exploit this by triggering discard failures, leading to resource exhaustion and a Denial of Service (DoS) on the affected system.
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Description OSIDB Bzimport 2026-08-15 06:11:49 UTC 
In the Linux kernel, the following vulnerability has been resolved:

md/raid10: fix writes_pending and barrier reference leaks on discard failures

raid10_make_request() acquires a writes_pending reference with
md_write_start() before calling raid10_handle_discard(). Several failure
paths in raid10_handle_discard() complete the bio and return without
releasing the corresponding reference, causing md_write_end() to be
skipped.

Call md_write_end() before returning from these failure paths to keep
writes_pending accounting balanced.

Additionally, discard split allocation failures can occur after
wait_barrier() succeeds. Those paths return without calling
allow_barrier(), leaking the associated barrier reference.

Release the barrier before returning from those paths.
Comment 1 gkamathe 2026-08-18 10:07:14 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081528-CVE-2026-72438-f2cb@gregkh/T