Description

In the Linux kernel, the following vulnerability has been resolved: drm: Set old handle to NULL before prime swap in change_handle There was a potential race condition in change_handle. The ioctl briefly had a single object with two idr entries; a concurrent gem_close could delete the object and remove one of the handles while leaving the other one dangling, which could subsequently be dereferenced for a use-after-free. To fix this, do the same dance that gem_close itself does. (f6cd7daecff5 drm: Release driver references to handle before making it available again) First idr_replace the old handle to NULL. Later, if the prime operations are successful, actually close it. create_tail required a similar dance to avoid a similar problem. (bd46cece51a3 drm/gem: Fix race in drm_gem_handle_create_tail()) It idr_allocs the new handle with NULL, then swaps in the correct object later to avoid races. We don't need to do that here, since the only operations that could race are drm_prime, and change_handle holds the prime lock for the entire duration. v2: cleanups of error paths

Weaknesses 1

Affected Products 4

References 3

• git.kernel.org https://git.kernel.org/stable/c/5e28b7b94408897e41c63477aabc9e1db439bc8c
  Patch
• git.kernel.org https://git.kernel.org/stable/c/61bd96d3e5472c253f9c1ab77608f0c8aaa9d025
  Patch
• git.kernel.org https://git.kernel.org/stable/c/672464dd53231509c9c771110798c56d4660e19e
  Patch

Remediation

• git.kernel.org https://git.kernel.org/stable/c/5e28b7b94408897e41c63477aabc9e1db439bc8c
  Patch
• git.kernel.org https://git.kernel.org/stable/c/61bd96d3e5472c253f9c1ab77608f0c8aaa9d025
  Patch
• git.kernel.org https://git.kernel.org/stable/c/672464dd53231509c9c771110798c56d4660e19e
  Patch