From: Nicholas Kazlauskas Date: Fri, 17 Dec 2021 19:18:59 +0000 (-0500) Subject: drm/amd/display: Fix USB4 null pointer dereference in update_psp_stream_config X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=33bb63915fee190102cae7d6576bc51a0bc342b2;p=linux.git drm/amd/display: Fix USB4 null pointer dereference in update_psp_stream_config [Why] A porting error on a previous patch left the block of code that causes the crash from a NULL pointer dereference. More specifically, we try to access link_enc before it's assigned in the USB4 case in the following assignment: config.dio_output_idx = link_enc->transmitter - TRANSMITTER_UNIPHY_A; [How] That assignment occurs later depending on the ASIC version. It's only needed on DCN31 and only after link_enc is already assigned. Fixes: 986430446c917b ("drm/amd/display: fix a crash on USB4 over C20 PHY") Reviewed-by: Harry Wentland Signed-off-by: Nicholas Kazlauskas Signed-off-by: Alex Deucher --- diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c index c8457babfdea4..c0bdc23702c83 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -3945,12 +3945,9 @@ static void update_psp_stream_config(struct pipe_ctx *pipe_ctx, bool dpms_off) config.dig_be = pipe_ctx->stream->link->link_enc_hw_inst; #if defined(CONFIG_DRM_AMD_DC_DCN) config.stream_enc_idx = pipe_ctx->stream_res.stream_enc->id - ENGINE_ID_DIGA; - + if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_PHY || pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA) { - link_enc = pipe_ctx->stream->link->link_enc; - config.dio_output_type = pipe_ctx->stream->link->ep_type; - config.dio_output_idx = link_enc->transmitter - TRANSMITTER_UNIPHY_A; if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_PHY) link_enc = pipe_ctx->stream->link->link_enc; else if (pipe_ctx->stream->link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)