CVE-2022-50417

In the Linux kernel, the following vulnerability has been resolved:

drm/panfrost: Fix GEM handle creation ref-counting

panfrost_gem_create_with_handle() previously returned a BO but with the only reference being from the handle, which user space could in theory guess and release, causing a use-after-free. Additionally if the call to panfrost_gem_mapping_get() in panfrost_ioctl_create_bo() failed then a(nother) reference on the BO was dropped.

The _create_with_handle() is a problematic pattern, so ditch it and instead create the handle in panfrost_ioctl_create_bo(). If the call to panfrost_gem_mapping_get() fails then this means that user space has indeed gone behind our back and freed the handle. In which case just return an error code.

This vulnerability does not affect Red Hat Enterprise Linux or related distributions because the Panfrost DRM graphics driver is not enabled or present in supported Red Hat kernels. In upstream environments with supported ARM Mali hardware, this flaw could allow a local unprivileged attacker to induce a use-after-free condition via improper buffer object reference counting, potentially causing a system crash or privilege escalation. Because the vulnerable code is not included in Red Hat enterprise products, supported systems are not exposed to this risk.