Commit 6c92f6d9 authored by Harry Wentland's avatar Harry Wentland Committed by Alex Deucher
Browse files

drm/amd/display: Validate payload length and link_index in dc_process_dmub_aux_transfer_async 



[Why&How]
dc_process_dmub_aux_transfer_async() copies payload->length bytes into a
16-byte stack buffer (dpaux.data[16]) guarded only by an ASSERT(), which
is a no-op in release builds. If a caller ever passes length > 16 this
results in a stack buffer overflow via memcpy.

Additionally, link_index is used to dereference dc->links[] without
bounds checking against dc->link_count, risking an out-of-bounds access.

Replace the ASSERT with a hard runtime check that returns false when
payload->length exceeds the destination buffer size, and add a bounds
check for link_index before it is used.

Assisted-by: GitHub Copilot:Claude claude-4-opus
Reviewed-by: default avatarAlex Hung <alex.hung@amd.com>
Signed-off-by: default avatarHarry Wentland <harry.wentland@amd.com>
Signed-off-by: default avatarIvan Lipski <ivan.lipski@amd.com>
Tested-by: default avatarDan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
(cherry picked from commit ba4caa9fecdf7a38f98c878ad05a8a64148b6881)
Cc: stable@vger.kernel.org
parent 86d2b206

drivers/gpu/drm/amd/display/dc/core/dc.c

+5 −1
Original line number Diff line number Diff line
@@ -6071,7 +6071,11 @@ bool dc_process_dmub_aux_transfer_async(struct dc *dc, 
	uint8_t action;

	union dmub_rb_cmd cmd = {0};



	ASSERT(payload->length <= 16);

	if (link_index >= dc->link_count || !dc->links[link_index])

		return false;



	if (payload->length > sizeof(cmd.dp_aux_access.aux_control.dpaux.data))

		return false;



	cmd.dp_aux_access.header.type = DMUB_CMD__DP_AUX_ACCESS;

	cmd.dp_aux_access.header.payload_bytes = 0;