Patch "drm/amd/display: Add null check for head_pipe in dcn201_acquire_free_pipe_for_layer" has been added to the 6.10-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 head_pipe in dcn201_acquire_free_pipe_for_layer

to the 6.10-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-head_pipe-in-dcn2.patch
and it can be found in the queue-6.10 subdirectory.

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



commit 242bd6becd5cfaf0ffc77fc8b27c2e8db2c507e3
Author: Srinivasan Shanmugam <srinivasan.shanmugam@xxxxxxx>
Date:   Sun Jul 21 19:18:58 2024 +0530

    drm/amd/display: Add null check for head_pipe in dcn201_acquire_free_pipe_for_layer
    
    [ Upstream commit f22f4754aaa47d8c59f166ba3042182859e5dff7 ]
    
    This commit addresses a potential null pointer dereference issue in the
    `dcn201_acquire_free_pipe_for_layer` function. The issue could occur
    when `head_pipe` is null.
    
    The fix adds a check to ensure `head_pipe` is not null before asserting
    it. If `head_pipe` is null, the function returns NULL to prevent a
    potential null pointer dereference.
    
    Reported by smatch:
    drivers/gpu/drm/amd/amdgpu/../display/dc/resource/dcn201/dcn201_resource.c:1016 dcn201_acquire_free_pipe_for_layer() error: we previously assumed 'head_pipe' could be null (see line 1010)
    
    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/resource/dcn201/dcn201_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dcn201/dcn201_resource.c
index 070a4efb308bd..1aeede348bd39 100644
--- a/drivers/gpu/drm/amd/display/dc/resource/dcn201/dcn201_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dcn201/dcn201_resource.c
@@ -1005,8 +1005,10 @@ static struct pipe_ctx *dcn201_acquire_free_pipe_for_layer(
 	struct pipe_ctx *head_pipe = resource_get_otg_master_for_stream(res_ctx, opp_head_pipe->stream);
 	struct pipe_ctx *idle_pipe = resource_find_free_secondary_pipe_legacy(res_ctx, pool, head_pipe);
 
-	if (!head_pipe)
+	if (!head_pipe) {
 		ASSERT(0);
+		return NULL;
+	}
 
 	if (!idle_pipe)
 		return NULL;