CVE-2022-49203

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

drm/amd/display: Fix double free during GPU reset on DC streams

[Why] The issue only occurs during the GPU reset code path.

We first backup the current state prior to commiting 0 streams internally from DM to DC. This state backup contains valid link encoder assignments.

DC will clear the link encoder assignments as part of current state (but not the backup, since it was a copied before the commit) and free the extra stream reference it held.

DC requires that the link encoder assignments remain cleared/invalid prior to commiting. Since the backup still has valid assignments we call the interface post reset to clear them. This routine also releases the extra reference that the link encoder interface held - resulting in a double free (and eventually a NULL pointer dereference).

[How] We'll have to do a full DC commit anyway after GPU reset because the stream count previously went to 0.

We don't need to retain the assignment that we had backed up, so just copy off of the now clean current state assignment after the reset has occcurred with the new link_enc_cfg_copy() interface.

This vulnerability is rated as Moderate impact because exploitation requires local access on systems equipped with specific AMD graphics hardware, limiting the attack scope to a local denial of service. The flaw occurs exclusively during GPU reset routines when handling display core stream states, requiring abnormal hardware error conditions or privileged actions to trigger. Supported Red Hat Enterprise Linux releases are not affected, as the vulnerable upstream code was never introduced into product kernels.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.