CVE-2026-68235

Summary

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

drm/amd/display: dce100: skip non-DP stream encoders for DP MST

On DCE8-class ASICs (e.g. Bonaire), the resource pool contains digital DIG stream encoders plus one analog DAC encoder. When assigning a stream encoder for a second DisplayPort MST stream, if the preferred digital encoder is already acquired, dce100_find_first_free_match_stream_enc_for_link() falls back to the first free pool entry. That entry may be the analog encoder, whose funcs table lacks DP hooks such as dp_set_stream_attribute. The subsequent atomic commit then dereferences NULL function pointers in link_set_dpms_on() and crashes.

Skip encoders without dp_set_stream_attribute when the stream uses a DP signal (including MST). Use dc_is_dp_signal(stream->signal) for the MST fallback path instead of checking only the link connector signal.

Tested on:

• GPU: AMD Radeon R7 260X (Bonaire / DCE8)
• Board: Supermicro C9X299-PG300
• Setup: DP MST daisy chain, hotplug second monitor or have it connected on boot
• Kernel: 7.1.3 (issue observed since 6.19)
• Result: kernel oops without patch; dual monitors stable with patch

(cherry picked from commit 28ec64943e3ee4d9b8d30cea61e380f1429953a8)

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/bfe28ce019c2d667d98071262da33d8bba122919
• https://git.kernel.org/stable/c/51ea665c30c424c98959101f3bf6f48ab42949c8
• https://git.kernel.org/stable/c/ed2d86aef9fa4c43f82da0fca91a60f7326d7d03
• https://git.kernel.org/stable/c/d340cba0df4cf327c7e89c7c1a4e79d4771d7dd5

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