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Vulnerability CVE-2021-47200
Published: 2024-04-10
| 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." |
References: |
https://git.kernel.org/stable/c/4f8e469a2384dfa4047145b0093126462cbb6dc0
https://git.kernel.org/stable/c/8244a3bc27b3efd057da154b8d7e414670d5044f
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