CVE-2021-47200 drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap
A use-after-free vulnerability in the Linux kernel's DRM subsystem allows attackers to execute arbitrary code or escalate privileges via crafted mmap operations.
- 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-2021-47200?
CVE-2021-47200 is a high-severity use after free vulnerability in Linux kernel, published on 10 Apr 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:
drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap
drm_gem_ttm_mmap() drops a reference to the gem object on success. If the gem object's refcount == 1 on entry to drm_gem_prime_mmap(), that drop will free the gem object, and the subsequent drm_gem_object_get() will be a UAF. Fix by grabbing a reference before calling the mmap helper.
This issue was forseen when the reference dropping was adding in commit 9786b65bc61ac ("drm/ttm: fix mmap refcounting"): "For that to work properly the drm_gem_object_get() call in drm_gem_ttm_mmap() must be moved so it happens before calling obj->funcs->mmap(), otherwise the gem refcount would go down to zero."
Weakness: CWE-416
Which versions are affected by CVE-2021-47200?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47200?
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-2021-47200 being exploited?
There is no known exploitation of CVE-2021-47200 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47200, GHSA-gf6p-hmwh-gpc7, ROOT-OS-DEBIAN-11-CVE-2021-47200, UBUNTU-CVE-2021-47200.