Bug 2464488 (CVE-2026-31767)

Summary: CVE-2026-31767 kernel: drm/i915/dsi: Don't do DSC horizontal timing adjustments in command mode
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the `drm/i915/dsi` module of the Linux kernel. Incorrect horizontal timing adjustments for Display Stream Compression (DSC) in command mode can lead to a division-by-zero error. This occurs when the adjusted horizontal total (`htotal`) becomes too small, causing the kernel to crash when determining the vertical total (`vtotal`). This vulnerability could result in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-05-01 15:09:36 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/i915/dsi: Don't do DSC horizontal timing adjustments in command mode

Stop adjusting the horizontal timing values based on the
compression ratio in command mode. Bspec seems to be telling
us to do this only in video mode, and this is also how the
Windows driver does things.

This should also fix a div-by-zero on some machines because
the adjusted htotal ends up being so small that we end up with
line_time_us==0 when trying to determine the vtotal value in
command mode.

Note that this doesn't actually make the display on the
Huawei Matebook E work, but at least the kernel no longer
explodes when the driver loads.

(cherry picked from commit 0b475e91ecc2313207196c6d7fd5c53e1a878525)
Comment 1 Keith Grant 2026-05-01 22:53:51 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050147-CVE-2026-31767-cfcf@gregkh/T