CVE-2025-39870 dmaengine: idxd: Fix double free in idxd_setup_wqs()
A double free vulnerability in the Linux kernel's idxd driver allows attackers to cause a denial of service or potentially execute arbitrary code.
- 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-2025-39870?
CVE-2025-39870 is a high-severity use after free vulnerability in Debian Debian Linux, published on 23 Sep 2025. 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:
dmaengine: idxd: Fix double free in idxd_setup_wqs()
The clean up in idxd_setup_wqs() has had a couple bugs because the error handling is a bit subtle. It's simpler to just re-write it in a cleaner way. The issues here are:
1) If "idxd->max_wqs" is <= 0 then we call put_device(conf_dev) when "conf_dev" hasn't been initialized. 2) If kzalloc_node() fails then again "conf_dev" is invalid. It's either uninitialized or it points to the "conf_dev" from the previous iteration so it leads to a double free.
It's better to free partial loop iterations within the loop and then the unwinding at the end can handle whole loop iterations. I also renamed the labels to describe what the goto does and not where the goto was located.
Weakness: CWE-415
Which versions are affected by CVE-2025-39870?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39870?
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-2025-39870 being exploited?
There is no known exploitation of CVE-2025-39870 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-39870, DEBIAN-CVE-2025-39870, GHSA-c3f5-89cx-rxg5, UBUNTU-CVE-2025-39870.