drm/amd/display: Handle null 'stream_status' in 'planes_changed_for_existing_stream'

stable inclusion
from stable-v6.6.55
commit 4778982c73d6c9f3fdbdbc6b6c8aa18df98251af
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRAU
CVE: CVE-2024-49912

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4778982c73d6c9f3fdbdbc6b6c8aa18df98251af



--------------------------------

[ Upstream commit 8141f21b941710ecebe49220b69822cab3abd23d ]

This commit adds a null check for 'stream_status' in the function
'planes_changed_for_existing_stream'. Previously, the code assumed
'stream_status' could be null, but did not handle the case where it was
actually null. This could lead to a null pointer dereference.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_resource.c:3784 planes_changed_for_existing_stream() error: we previously assumed 'stream_status' could be null (see line 3774)

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>
Signed-off-by: Cai Xinchen <caixinchen1@huawei.com>