drm/amd/display: Add null check for head_pipe in dcn32_acquire_idle_pipe_for_head_pip...

[ Upstream commit ac2140449184a26eac99585b7f69814bd3ba8f2d ]

This commit addresses a potential null pointer dereference issue in the
`dcn32_acquire_idle_pipe_for_head_pipe_in_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/dcn32/dcn32_resource.c:2690 dcn32_acquire_idle_pipe_for_head_pipe_in_layer() error: we previously assumed 'head_pipe' could be null (see line 2681)

Cc: Tom Chung <chiahsuan.chung@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c
index d84c8e0e5c2f03008e8662a2613a4ad8a1b79b49..9209bcad699a880f03b8ef531a4a675e389e70a3 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c
@@ -2664,8 +2664,10 @@ static struct pipe_ctx *dcn32_acquire_idle_pipe_for_head_pipe_in_layer(
        struct resource_context *old_ctx = &stream->ctx->dc->current_state->res_ctx;
        int head_index;
 
-       if (!head_pipe)
+       if (!head_pipe) {
                ASSERT(0);
+               return NULL;
+       }
 
        /*
         * Modified from dcn20_acquire_idle_pipe_for_layer