Bug 2516325 (CVE-2026-72218)

Summary: CVE-2026-72218 kernel: lockd: Plug nlm_file refcount leak on cached nlm_do_fopen() failure
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 lockd component. A reference count leak occurs when nlm_do_fopen() fails on a cached file path. This prevents the file's reference count from returning to zero, causing a resource leak. Over time, this can lead to resource exhaustion and a Denial of Service (DoS) condition.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-08-15 06:06:40 UTC 
In the Linux kernel, the following vulnerability has been resolved:

lockd: Plug nlm_file refcount leak on cached nlm_do_fopen() failure

The cached-file path in nlm_lookup_file() reaches the found: label
unconditionally, even when nlm_do_fopen() fails. At that label
*result and file->f_count are updated before the error is returned.
The wrappers nlm3svc_lookup_file() and nlm4svc_lookup_file() then
bail out of their switch without copying *result back to their
caller, so the proc handler's local nlm_file pointer remains NULL
and the cleanup path skips nlm_release_file(). The f_count
increment is never released, and nlm_traverse_files() can no
longer reap the file because its refcount never returns to zero
between requests.

Short-circuit the cached path so neither *result nor f_count is
touched when nlm_do_fopen() fails on a hashed nlm_file.
Comment 1 gkamathe 2026-08-18 06:33:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081547-CVE-2026-72218-9e91@gregkh/T