CVE-2026-46263 — drm/amd/display: Fix out-of-bounds stream encoder index v3

Affected: Linux

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

drm/amd/display: Fix out-of-bounds stream encoder index v3

eng_id can be negative and that stream_enc_regs[] can be indexed out of bounds.

eng_id is used directly as an index into stream_enc_regs[], which has only 5 entries. When eng_id is 5 (ENGINE_ID_DIGF) or negative, this can access memory past the end of the array.

Add a bounds check using ARRAY_SIZE() before using eng_id as an index. The unsigned cast also rejects negative values.

This avoids out-of-bounds access.

Fixes the below smatch error: dcn*_resource.c: stream_encoder_create() may index stream_enc_regs[eng_id] out of bounds (size 5).

drivers/gpu/drm/amd/amdgpu/../display/dc/resource/dcn351/dcn351_resource.c 1246 static struct stream_encoder *dcn35_stream_encoder_create( 1247 enum engine_id eng_id, 1248 struct dc_context *ctx) 1249 {

...

1255 1256 /* Mapping of VPG, AFMT, DME register blocks to DIO block instance */ 1257 if (eng_id <= ENGINE_ID_DIGF) {

ENGINE_ID_DIGF is 5. should <= be <?

Unrelated but, ugh, why is Smatch saying that "eng_id" can be negative? end_id is type signed long, but there are checks in the caller which prevent it from being negative.

1258 vpg_inst = eng_id; 1259 afmt_inst = eng_id; 1260 } else 1261 return NULL; 1262

...

1281 1282 dcn35_dio_stream_enc…

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CVE-2026-46263 — drm/amd/display: Fix out-of-bounds stream encoder index v3