Summary

dce4_hdmi_set_color_depth L342 connector=radeon_get_connector_for_encoder(encoder) no NULL check before connector->name in DRM_DEBUG L355/361/367. radeon_get_connector_for_encoder returns NULL when active_device matches no connector on unlocked connector_list. Sibling evergreen_hdmi_enable L437 and evergreen_dp_enable L476 explicitly test connector&&. DRM_DEBUG evaluates args unconditionally before drm_dbg early-return so crash not gated on drm_debug. Caller radeon_hdmi_set_color_depth radeon_audio.c:657 only checks dig&&dig->afmt not connector. Reachable: race display hot-unplug/MST reconfig against mode_set. NULL deref on connector->name load offset ~40. Local DoS panic. Fix: conn_name = connector?connector->name:none.

PoC verification

Evidence pack

findings/poc/DF-1934 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	439 B	view raw
VERDICT.md	verdict	source-confirmation analysis	1.0 KB	↓ raw
build.sh	build-script	N/A (source-only)	65 B	view raw
run.sh	run-script	N/A (source-only)	89 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1934 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: dce4_hdmi_set_color_depth L342 connector=radeon_get_connector_for_encoder(encoder) no NULL check before connector->name in DRM_DEBUG L355/361/367. radeon_get_connector_for_encoder returns NULL when ac

Citation: sys/dev/drm/radeon/evergreen_hdmi.c:342-367

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix status (batch validation)

Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest make -j6 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: connector->name NULL deref in DRM_DEBUG (evergreen_hdmi.c:342-367)

Verified recommended fix

Source-confirmed: connector->name NULL deref in DRM_DEBUG (evergreen_hdmi.c:342-367)

Verdict