CVE-2026-53126: blk-cgroup: fix disk reference leak in blkcg_maybe_throttle_current()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-24 · updated 2026-07-23

Description

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.

Affected products

Linux kernel: from 6.3 before 6.6.141; from 6.7 before 6.12.91; from 6.13 before 6.18.33; from 6.19 before 7.0.10 — fixed in 6.12.91, 6.18.33, 6.6.141, 7.0.10

How to fix

Upgrade to a fixed version: Linux kernel 6.12.91, 6.18.33, 6.6.141, 7.0.10. Check the vendor advisory for mitigations.

References

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