CVE-2024-39496 btrfs: zoned: fix use-after-free due to race with dev replace
A race condition in the Linux kernel btrfs zoned module allows a use-after-free during device replacement, potentially leading to code execution or privilege escalation.
- 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-2024-39496?
CVE-2024-39496 is a high-severity use after free vulnerability in Debian Debian Linux, published on 12 Jul 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:
btrfs: zoned: fix use-after-free due to race with dev replace
While loading a zone's info during creation of a block group, we can race with a device replace operation and then trigger a use-after-free on the device that was just replaced (source device of the replace operation).
This happens because at btrfs_load_zone_info() we extract a device from the chunk map into a local variable and then use the device while not under the protection of the device replace rwsem. So if there's a device replace operation happening when we extract the device and that device is the source of the replace operation, we will trigger a use-after-free if before we finish using the device the replace operation finishes and frees the device.
Fix this by enlarging the critical section under the protection of the device replace rwsem so that all uses of the device are done inside the critical section.
Weakness: CWE-416
Which versions are affected by CVE-2024-39496?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2024-39496?
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-2024-39496 being exploited?
There is no known exploitation of CVE-2024-39496 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2024-39496, DEBIAN-CVE-2024-39496, GHSA-gc3v-ppv7-rpm9, UBUNTU-CVE-2024-39496.