CVE-2021-46937 mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()'
Repeated writes to the DAMON debugfs target_ids file leak memory, potentially causing a denial of service in the Linux kernel.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-46937?
CVE-2021-46937 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()'
DAMON debugfs interface increases the reference counts of 'struct pid's for targets from the 'target_ids' file write callback ('dbgfs_target_ids_write()'), but decreases the counts only in DAMON monitoring termination callback ('dbgfs_before_terminate()').
Therefore, when 'target_ids' file is repeatedly written without DAMON monitoring start/termination, the reference count is not decreased and therefore memory for the 'struct pid' cannot be freed. This commit fixes this issue by decreasing the reference counts when 'target_ids' is written.
Weakness: CWE-668
Which versions are affected by CVE-2021-46937?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-46937?
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-2021-46937 being exploited?
There is no known exploitation of CVE-2021-46937 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-46937, GHSA-2hrm-9gxc-3c35, ROOT-OS-DEBIAN-11-CVE-2021-46937, UBUNTU-CVE-2021-46937.