CVE-2026-98786

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

drm/amd/display: guard dc sink dereferences in MST mode validation

dm dp mst is port support mode() reads aconnector->dc sink->dsc caps... for the DSC branch-throughput check, and get conv frl bw()'s HDMI-PCON FRL-bandwidth path reads aconnector->dc sink->edid caps.max frl rate, both without a NULL check. dc sink is cleared asynchronously on MST unplug, and both functions run from paths that the driver's own comments document as racing that teardown: the connector probe worker's ->mode valid callback and a compositor's atomic check, neither of which holds the MST manager lock that the teardown path uses. The former does have an existing dsc aux NULL check, but dsc aux isn't reliably cleared in every path that clears dc sink, so it doesn't cover this.

Fail the port-support check and skip the FRL conversion path when the sink is already gone.

(cherry picked from commit 7c3db8da4e039698ae198c870712428644e965c7)