CVE-2024-53140 netlink: terminate outstanding dump on socket close
A use-after-free vulnerability in the Linux kernel netlink subsystem allows local attackers to cause denial of service or potentially escalate privileges.
- 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-2024-53140?
CVE-2024-53140 is a high-severity use after free vulnerability in Linux kernel, published on 4 Dec 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:
netlink: terminate outstanding dump on socket close
Netlink supports iterative dumping of data. It provides the families the following ops: - start - (optional) kicks off the dumping process - dump - actual dump helper, keeps getting called until it returns 0 - done - (optional) pairs with .start, can be used for cleanup The whole process is asynchronous and the repeated calls to .dump don't actually happen in a tight loop, but rather are triggered in response to recvmsg() on the socket.
This gives the user full control over the dump, but also means that the user can close the socket without getting to the end of the dump. To make sure .start is always paired with .done we check if there is an ongoing dump before freeing the socket, and if so call .done.
The complication is that sockets can get freed from BH and .done is allowed to sleep. So we use a workqueue to defer the call, when needed.
Unfortunately this does not work correctly. What we defer is not the cleanup but rather releasing a reference on the socket. We have no guarantee that we own the last reference, if someone else holds the socket they may release it in BH and we're back to square one.
The whole dance, however, appears to be unnecessary. Only the user can interact with dumps, so we can clean up when socket is closed. And close always happens in process context. Some async code may still access the socket after close, queue notification skbs to it etc. but no dumps can start, end or otherwise make progress.
Delete the workqueue and flush the dump state directly from the release handler. Note that further cleanup is possible in -next, for instance we now always call .done before releasing the main module reference, so dump doesn't have to take a reference of its own.
Which versions are affected by CVE-2024-53140?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-53140?
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-2024-53140 being exploited?
There is no known exploitation of CVE-2024-53140 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-54183, AZL-54197, BELL-CVE-2024-53140, DEBIAN-CVE-2024-53140, GHSA-pc3w-52r9-h2g7, UBUNTU-CVE-2024-53140.