CVE-2023-52836 locking/ww_mutex/test: Fix potential workqueue corruption
A use-after-free bug in the Linux kernel's ww_mutex test module can cause workqueue corruption and system crashes.
- 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-2023-52836?
CVE-2023-52836 is a high-severity use after free vulnerability in Linux kernel, published on 21 May 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:
locking/ww_mutex/test: Fix potential workqueue corruption
In some cases running with the test-ww_mutex code, I was seeing odd behavior where sometimes it seemed flush_workqueue was returning before all the work threads were finished.
Often this would cause strange crashes as the mutexes would be freed while they were being used.
Looking at the code, there is a lifetime problem as the controlling thread that spawns the work allocates the "struct stress" structures that are passed to the workqueue threads. Then when the workqueue threads are finished, they free the stress struct that was passed to them.
Unfortunately the workqueue work_struct node is in the stress struct. Which means the work_struct is freed before the work thread returns and while flush_workqueue is waiting.
It seems like a better idea to have the controlling thread both allocate and free the stress structures, so that we can be sure we don't corrupt the workqueue by freeing the structure prematurely.
So this patch reworks the test to do so, and with this change I no longer see the early flush_workqueue returns.
Weakness: CWE-787
Which versions are affected by CVE-2023-52836?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-52836?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2023-52836 being exploited?
There is no known exploitation of CVE-2023-52836 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-52836, DEBIAN-CVE-2023-52836, GHSA-xj3r-45pc-vrfq, UBUNTU-CVE-2023-52836.