[PATCH 5.15.y] drm/amd/display: Add null checks for 'stream' and 'plane' before dereferencing

[PATCH 5.15.y] drm/amd/display: Add null checks for 'stream' and 'plane' before dereferencing

[Zhi Yang]

From: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>

commit 15c2990e0f0108b9c3752d7072a97d45d4283aea upstream.

This commit adds null checks for the 'stream' and 'plane' variables in
the dcn30_apply_idle_power_optimizations function. These variables were
previously assumed to be null at line 922, but they were used later in
the code without checking if they were null. This could potentially lead
to a null pointer dereference, which would cause a crash.

The null checks ensure that 'stream' and 'plane' are not null before
they are used, preventing potential crashes.

Fixes the below static smatch checker:
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:938 dcn30_apply_idle_power_optimizations() error: we previously assumed 'stream' could be null (see line 922)
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:940 dcn30_apply_idle_power_optimizations() error: we previously assumed 'plane' could be null (see line 922)

Cc: Tom Chung <chiahsuan.chung@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Cc: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Hersen Wu <hersenxs.wu@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Harry Wentland <harry.wentland@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>
Signed-off-by: Zhi Yang <Zhi.Yang@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
---
Build test passed.
---
 drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
index 81547178a934..30716b88136c 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
@@ -784,6 +784,9 @@ bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 			stream = dc->current_state->streams[0];
 			plane = (stream ? dc->current_state->stream_status[0].plane_states[0] : NULL);
 
+			if (!stream || !plane)
+				return false;
+
 			if (stream && plane) {
 				cursor_cache_enable = stream->cursor_position.enable &&
 						plane->address.grph.cursor_cache_addr.quad_part;
-- 
2.34.1