CVE-2021-47200

Summary

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."

Affected Software

VendorProductVersion RangeStatus
LinuxLinux9786b65bc61acec63f923978c75e707afbb74bc7 < 4f8e469a2384dfa4047145b0093126462cbb6dc0affected
LinuxLinux9786b65bc61acec63f923978c75e707afbb74bc7 < 8244a3bc27b3efd057da154b8d7e414670d5044faffected
LinuxLinux5.5affected
LinuxLinux0 < 5.5unaffected
LinuxLinux5.15.5 <= 5.15.*unaffected
LinuxLinux5.16 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

CVE Program Container

Additional References

References