CVE-2026-46245: drm/amd/display: Fix dc_link NULL handling in HPD init

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

drm/amd/display: Fix dclink NULL handling in HPD init

amdgpudmhpdinit() may see connectors without a valid dclink.

The code already checks dclink for the polling decision, but later unconditionally dereferences it when setting up HPD interrupts.

Assign dclink early and skip connectors where it is NULL.

Fixes the below: drivers/gpu/drm/amd/amdgpu/../display/amdgpudm/amdgpudmirq.c:940 amdgpudmhpdinit() error: we previously assumed 'dclink' could be null (see line 931)

drivers/gpu/drm/amd/amdgpu/../display/amdgpudm/amdgpudmirq.c 923 / 924 Analog connectors may be hot-plugged unlike other connector 925 types that don't support HPD. Only poll analog connectors. 926 / 927 usepolling |= 928 amdgpudmconnector->dclink && ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The patch adds this NULL check but hopefully it can be removed

929 dcconnectorsupportsanalog(amdgpudmconnector->dclink->linkid.id); 930 931 dclink = amdgpudmconnector->dclink;

dclink assigned here.

932 933 / 934 Get a base driver irq reference for hpd ints for the lifetime 935 of dm. Note that only hpd interrupt types are registered with 936 base driver; hpdrx types aren't. IOW, amdgpuirqget/put on 937 hpdrx isn't available. DM currently controls hpdrx 938 explicitly with dcinterruptset() 939 / --> 940 if (dclink->irqsourcehpd != DCIRQSOURCEINVALID) { ^^^^^^^^^^^^^^^^^^^^^^^ If it's NULL then we are trouble because we dereference it here.

941 irqtype = dclink->irqsourcehpd - DCIRQSOURCEHPD1; 942 / 943 TODO: There's a mismatch between modeinfo.numhpd 944 and what bios reports as the # of connectors with hpd