Bug 2454875 (CVE-2026-31400)

Summary: CVE-2026-31400 kernel: sunrpc: fix cache_request leak in cache_release
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 sunrpc component. When a reader's file descriptor is closed during an active cache request read, the system fails to properly free the associated memory. This memory leak can be exploited by a local attacker, potentially leading to a Denial of Service (DoS) by exhausting system resources.
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Description OSIDB Bzimport 2026-04-03 16:05:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

sunrpc: fix cache_request leak in cache_release

When a reader's file descriptor is closed while in the middle of reading
a cache_request (rp->offset != 0), cache_release() decrements the
request's readers count but never checks whether it should free the
request.

In cache_read(), when readers drops to 0 and CACHE_PENDING is clear, the
cache_request is removed from the queue and freed along with its buffer
and cache_head reference. cache_release() lacks this cleanup.

The only other path that frees requests with readers == 0 is
cache_dequeue(), but it runs only when CACHE_PENDING transitions from
set to clear. If that transition already happened while readers was
still non-zero, cache_dequeue() will have skipped the request, and no
subsequent call will clean it up.

Add the same cleanup logic from cache_read() to cache_release(): after
decrementing readers, check if it reached 0 with CACHE_PENDING clear,
and if so, dequeue and free the cache_request.
Comment 1 Jon Moroney 2026-04-03 16:28:51 UTC Comment hidden (spam)