Patch "drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for_stream" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for_stream

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-add-null-check-for-top_pipe_to_progr.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f387763f7b8015631667f53887014aa73baaa303
Author: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx>
Date:   Thu Jul 25 07:23:48 2024 +0530

    drm/amd/display: Add null check for top_pipe_to_program in commit_planes_for_stream
    
    [ Upstream commit 66d71a72539e173a9b00ca0b1852cbaa5f5bf1ad ]
    
    This commit addresses a null pointer dereference issue in the
    `commit_planes_for_stream` function at line 4140. The issue could occur
    when `top_pipe_to_program` is null.
    
    The fix adds a check to ensure `top_pipe_to_program` is not null before
    accessing its stream_res. This prevents a null pointer dereference.
    
    Reported by smatch:
    drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:4140 commit_planes_for_stream() error: we previously assumed 'top_pipe_to_program' could be null (see line 3906)
    
    Cc: Tom Chung <chiahsuan.chung@xxxxxxx>
    Cc: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
    Cc: Roman Li <roman.li@xxxxxxx>
    Cc: Alex Hung <alex.hung@xxxxxxx>
    Cc: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>
    Cc: Harry Wentland <harry.wentland@xxxxxxx>
    Cc: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
    Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx>
    Reviewed-by: Tom Chung <chiahsuan.chung@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 50e643bfdfbad..0b2eb2a6c8e14 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -3797,7 +3797,8 @@ static void commit_planes_for_stream(struct dc *dc,
 	}
 
 	if ((update_type != UPDATE_TYPE_FAST) && stream->update_flags.bits.dsc_changed)
-		if (top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
+		if (top_pipe_to_program &&
+		    top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
 			top_pipe_to_program->stream_res.tg->funcs->wait_for_state(
 				top_pipe_to_program->stream_res.tg,
 				CRTC_STATE_VACTIVE);