vulnerability
Debian: CVE-2021-47200: linux -- security update
Severity | CVSS | Published | Added | Modified |
---|---|---|---|---|
7 | (AV:L/AC:L/Au:S/C:C/I:C/A:C) | 04/10/2024 | 07/30/2024 | 01/30/2025 |
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."
Solution

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