CVE-2026-74449: drm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Fix divide-by-zero in calculatemcachesetting on zero viewport
If a plane reaches calculatemcachesetting with a zero-area viewport, calculatemcachesetting exits early with nummcaches == 0 and mvmpgwidth/height == 0. This will cause a divide-by-zero panic and can also cause an underflow on nummcaches.
Fix this by changing calculatemcachesetting to bool and adding guards after each calculatemcacherowbytes call. If nummcaches or mvmpgwidth/height is zero, return a false. Callers will propagate the failure as a rejected mode, which prevents the panic.
(cherry picked from commit 29c0f7c655f47bcbd575ff75e58480df6ec3c9da)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
In drm/amd/display, change calculate_mcache_setting to return bool and add guards: if num_mcaches==0 exit early (rejected mode to prevent panic), and if mvmpg_width/height == 0 (e.g., zero-area viewport) return false before calling calculate_mcache_row_bytes.
Linux kernel (drm/amd/display) calculate_mcache_setting return type and guards = bool; if num_mcaches==0 or mvmpg_width/height==0 then return false / exit early
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74449?
CVE-2026-74449 has a risk rating of 34, indicating it is a low to moderate severity vulnerability.
How do I fix CVE-2026-74449?
To fix CVE-2026-74449, you should update your Linux kernel to the latest patched version that addresses this divide-by-zero vulnerability.
What systems are affected by CVE-2026-74449?
CVE-2026-74449 affects systems running the Linux kernel with the AMD display driver that could encounter a zero-area viewport.
What type of vulnerability is CVE-2026-74449?
CVE-2026-74449 is a divide-by-zero vulnerability found in the calculate_mcache_setting function.
Is CVE-2026-74449 being actively exploited?
As of now, there are no known active exploits for CVE-2026-74449 in the wild.