Bug 2466988 (CVE-2026-43106)

Summary: CVE-2026-43106 kernel: cachefiles: fix incorrect dentry refcount in cachefiles_cull()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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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 cachefiles module, which manages cached files. This vulnerability stems from an error in how the system counts references to certain file system objects, specifically within the cachefiles_cull() function. When a reference is lost, it can lead to system instability. This could potentially result in a denial of service (DoS), making the system unavailable to users.
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Description OSIDB Bzimport 2026-05-06 10:02:00 UTC 
In the Linux kernel, the following vulnerability has been resolved:

cachefiles: fix incorrect dentry refcount in cachefiles_cull()

The patch mentioned below changed cachefiles_bury_object() to expect 2
references to the 'rep' dentry.  Three of the callers were changed to
use start_removing_dentry() which takes an extra reference so in those
cases the call gets the expected references.

However there is another call to cachefiles_bury_object() in
cachefiles_cull() which did not need to be changed to use
start_removing_dentry() and so was not properly considered.
It still passed the dentry with just one reference so the net result is
that a reference is lost.

To meet the expectations of cachefiles_bury_object(), cachefiles_cull()
must take an extra reference before the call.  It will be dropped by
cachefiles_bury_object().
Comment 1 Alexander B 2026-05-06 15:02:58 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050623-CVE-2026-43106-df89@gregkh/T