linux-kernel - [PATCH AUTOSEL 6.6 11/20] drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_handle_cursor

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Message-ID: <20240728154605.2048490-11-sashal@kernel.org>
Date: Sun, 28 Jul 2024 11:45:09 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Srinivasan Shanmugam <srinivasan.shanmugam@....com>,
	Tom Chung <chiahsuan.chung@....com>,
	Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
	Roman Li <roman.li@....com>,
	Hersen Wu <hersenxs.wu@....com>,
	Alex Hung <alex.hung@....com>,
	Aurabindo Pillai <aurabindo.pillai@....com>,
	Harry Wentland <harry.wentland@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	sunpeng.li@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	mwen@...lia.com,
	joshua@...ggi.es,
	hamza.mahfooz@....com,
	Qingqing.Zhuo@....com,
	Nicholas.Choi@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 11/20] drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_handle_cursor_update

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

[ Upstream commit 38e6f715b02b572f74677eb2f29d3b4bc6f1ddff ]

This commit adds a null check for the 'afb' variable in the
amdgpu_dm_plane_handle_cursor_update function. Previously, 'afb' was
assumed to be null, but was used later in the code without a null check.
This could potentially lead to a null pointer dereference.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_plane.c:1298 amdgpu_dm_plane_handle_cursor_update() error: we previously assumed 'afb' could be null (see line 1252)

Cc: Tom Chung <chiahsuan.chung@....com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Cc: Roman Li <roman.li@....com>
Cc: Hersen Wu <hersenxs.wu@....com>
Cc: Alex Hung <alex.hung@....com>
Cc: Aurabindo Pillai <aurabindo.pillai@....com>
Cc: Harry Wentland <harry.wentland@....com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@....com>
Reviewed-by: Harry Wentland <harry.wentland@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c  | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
index cc74dd69acf2b..eb77de95f26f5 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
@@ -1225,14 +1225,22 @@ void amdgpu_dm_plane_handle_cursor_update(struct drm_plane *plane,
 {
 	struct amdgpu_device *adev = drm_to_adev(plane->dev);
 	struct amdgpu_framebuffer *afb = to_amdgpu_framebuffer(plane->state->fb);
-	struct drm_crtc *crtc = afb ? plane->state->crtc : old_plane_state->crtc;
-	struct dm_crtc_state *crtc_state = crtc ? to_dm_crtc_state(crtc->state) : NULL;
-	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
-	uint64_t address = afb ? afb->address : 0;
+	struct drm_crtc *crtc;
+	struct dm_crtc_state *crtc_state;
+	struct amdgpu_crtc *amdgpu_crtc;
+	u64 address;
 	struct dc_cursor_position position = {0};
 	struct dc_cursor_attributes attributes;
 	int ret;
 
+	if (!afb)
+		return;
+
+	crtc = plane->state->crtc ? plane->state->crtc : old_plane_state->crtc;
+	crtc_state = crtc ? to_dm_crtc_state(crtc->state) : NULL;
+	amdgpu_crtc = to_amdgpu_crtc(crtc);
+	address = afb->address;
+
 	if (!plane->state->fb && !old_plane_state->fb)
 		return;
 
-- 
2.43.0