Bug 2532450 (CVE-2026-89548)

Summary: CVE-2026-89548 kernel: SUNRPC: always drain cache_cleaner before destroying a cache_detail
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's SUNRPC component. When `sunrpc_destroy_cache_detail()` is called, it may not properly drain the `cache_cleaner` before freeing a `cache_detail` object. This oversight can lead to a use-after-free vulnerability, where the system attempts to access or use memory that has already been deallocated. A local attacker could potentially exploit this to cause a denial of service or achieve privilege escalation.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 23:20:02 UTC 
In the Linux kernel, the following vulnerability has been resolved:

SUNRPC: always drain cache_cleaner before destroying a cache_detail

sunrpc_destroy_cache_detail() only cancels the global cache_cleaner
delayed_work when cache_list is empty.  During per-netns teardown
cache_list is never empty because init_net's caches remain registered,
so the cancel never fires.  After unlink, the caller proceeds to
cache_destroy_net() which kfrees the cache_detail while cache_clean()
may still hold a dangling pointer to it.  The result is a
use-after-free: cache_dequeue() takes cd->queue_lock on freed memory,
and cache_put() dereferences cd->cache_put as a function pointer from
freed slab.

Drop the list_empty guard so that cancel_delayed_work_sync() always
runs, ensuring any in-flight cache_clean() completes before the
cache_detail is freed.  Re-arm the cleaner afterwards if other caches
are still registered.
Comment 1 gkamathe 2026-09-15 13:05:55 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89548.mbox