The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Thanks, Sasha

------------------ original commit in Linus's tree ------------------

From 166225e79ccc3d02c4c46e1b3c09d03eb91473ca Mon Sep 17 00:00:00 2001 From: Srinivasan Shanmugam srinivasan.shanmugam@amd.com Date: Wed, 10 Jan 2024 20:58:35 +0530 Subject: [PATCH] drm/amd/display: Fix late derefrence 'dsc' check in 'link_set_dsc_pps_packet()'

In link_set_dsc_pps_packet(), 'struct display_stream_compressor *dsc' was dereferenced in a DC_LOGGER_INIT(dsc->ctx->logger); before the 'dsc' NULL pointer check.

Fixes the below: drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_dpms.c:905 link_set_dsc_pps_packet() warn: variable dereferenced before check 'dsc' (see line 903)

Cc: stable@vger.kernel.org Cc: Aurabindo Pillai aurabindo.pillai@amd.com Cc: Rodrigo Siqueira Rodrigo.Siqueira@amd.com Cc: Hamza Mahfooz hamza.mahfooz@amd.com Cc: Wenjing Liu wenjing.liu@amd.com Cc: Qingqing Zhuo qingqing.zhuo@amd.com Signed-off-by: Srinivasan Shanmugam srinivasan.shanmugam@amd.com Reviewed-by: Aurabindo Pillai aurabindo.pillai@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com --- drivers/gpu/drm/amd/display/dc/link/link_dpms.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c index 3de148004c066..3cbfbf8d107e9 100644 --- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c +++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c @@ -900,11 +900,15 @@ bool link_set_dsc_pps_packet(struct pipe_ctx *pipe_ctx, bool enable, bool immedi { struct display_stream_compressor *dsc = pipe_ctx->stream_res.dsc; struct dc_stream_state *stream = pipe_ctx->stream; - DC_LOGGER_INIT(dsc->ctx->logger);

- if (!pipe_ctx->stream->timing.flags.DSC || !dsc) + if (!pipe_ctx->stream->timing.flags.DSC) return false;

+ if (!dsc) + return false; + + DC_LOGGER_INIT(dsc->ctx->logger); + if (enable) { struct dsc_config dsc_cfg; uint8_t dsc_packed_pps[128];