CVE-2023-54227 blk-mq: fix tags leak when shrink nr_hw_queues
A memory leak in the Linux kernel block layer allows local attackers to exhaust system memory, potentially causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-54227?
CVE-2023-54227 is a high-severity denial of service vulnerability in Linux, published on 30 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
blk-mq: fix tags leak when shrink nr_hw_queues
Although we don't need to realloc set->tags[] when shrink nr_hw_queues, we need to free them. Or these tags will be leaked.
How to reproduce: 1. mount -t configfs configfs /mnt 2. modprobe null_blk nr_devices=0 submit_queues=8 3. mkdir /mnt/nullb/nullb0 4. echo 1 > /mnt/nullb/nullb0/power 5. echo 4 > /mnt/nullb/nullb0/submit_queues 6. rmdir /mnt/nullb/nullb0
In step 4, will alloc 9 tags (8 submit queues and 1 poll queue), then in step 5, new_nr_hw_queues = 5 (4 submit queues and 1 poll queue). At last in step 6, only these 5 tags are freed, the other 4 tags leaked.
Which versions are affected by CVE-2023-54227?
How do I fix CVE-2023-54227?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-54227 being exploited?
There is no known exploitation of CVE-2023-54227 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-54227, DEBIAN-CVE-2023-54227, GHSA-5vch-5hxh-2rq8, ROOT-OS-DEBIAN-12-CVE-2023-54227, ROOT-OS-UBUNTU-2204-CVE-2023-54227, UBUNTU-CVE-2023-54227.