Bug 2516997 (CVE-2026-74449)

Summary: CVE-2026-74449 kernel: drm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the display driver component of the Linux kernel. A local attacker could exploit a vulnerability related to how the system handles display settings, specifically when processing certain display configurations. This could lead to a system crash, resulting in a Denial of Service (DoS) for the affected system.
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Description OSIDB Bzimport 2026-08-15 12:43:51 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport

If a plane reaches calculate_mcache_setting with a zero-area viewport,
calculate_mcache_setting exits early with num_mcaches == 0 and
mvmpg_width/height == 0. This will cause a divide-by-zero panic and can
also cause an underflow on num_mcaches.

Fix this by changing calculate_mcache_setting to bool and adding guards
after each calculate_mcache_row_bytes call. If num_mcaches or
mvmpg_width/height is zero, return a false. Callers will propagate the
failure as a rejected mode, which prevents the panic.

(cherry picked from commit 29c0f7c655f47bcbd575ff75e58480df6ec3c9da)
Comment 1 gkamathe 2026-08-21 10:59:55 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081530-CVE-2026-74449-8eae@gregkh/T