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

[Srinivasan Shanmugam]

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 at amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
Cc: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
Cc: Roman Li <roman.li at amd.com>
Cc: Hersen Wu <hersenxs.wu at amd.com>
Cc: Alex Hung <alex.hung at amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai at amd.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
 drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c
index 29d1f150846a..4c4706153305 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn30/dcn30_hwseq.c
@@ -919,6 +919,9 @@ 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