Bug 2492412 (CVE-2026-53126)

Summary: CVE-2026-53126 kernel: blk-cgroup: fix disk reference leak in blkcg_maybe_throttle_current()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
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 `blk-cgroup` component. This vulnerability occurs due to a missing disk reference release on an error path within the `blkcg_maybe_throttle_current()` function. When certain lookups or gets fail, the disk reference acquired is not properly freed. This oversight can lead to resource exhaustion, potentially allowing a local attacker to cause a Denial of Service (DoS) by preventing the disk from being released.
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Description OSIDB Bzimport 2026-06-24 18:10:52 UTC 
In the Linux kernel, the following vulnerability has been resolved:

blk-cgroup: fix disk reference leak in blkcg_maybe_throttle_current()

Add the missing put_disk() on the error path in
blkcg_maybe_throttle_current(). When blkcg lookup, blkg lookup, or
blkg_tryget() fails, the function jumps to the out label which only
calls rcu_read_unlock() but does not release the disk reference acquired
by blkcg_schedule_throttle() via get_device(). Since current->throttle_disk
is already set to NULL before the lookup, blkcg_exit() cannot release
this reference either, causing the disk to never be freed.

Restore the reference release that was present as blk_put_queue() in the
original code but was inadvertently dropped during the conversion from
request_queue to gendisk.
Comment 1 Mauro Matteo Cascella 2026-06-24 19:09:19 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062417-CVE-2026-53126-f288@gregkh/T