linux-kernel - [PATCH AUTOSEL 6.11 156/244] drm/amd/display: Add null check for 'afb' in amdgpu_dm_update

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Message-ID: <20240925113641.1297102-156-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:26:17 -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>,
	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,
	hamza.mahfooz@....com,
	mario.limonciello@....com,
	Wayne.Lin@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.11 156/244] drm/amd/display: Add null check for 'afb' in amdgpu_dm_update_cursor (v2)

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

[ Upstream commit 0fe20258b4989b9112b5e9470df33a0939403fd4 ]

This commit adds a null check for the 'afb' variable in the
amdgpu_dm_update_cursor function. Previously, 'afb' was assumed to be
null at line 8388, but was used later in the code without a null check.
This could potentially lead to a null pointer dereference.

Changes since v1:
- Moved the null check for 'afb' to the line where 'afb' is used. (Alex)

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:8433 amdgpu_dm_update_cursor()
	error: we previously assumed 'afb' could be null (see line 8388)

Cc: Tom Chung <chiahsuan.chung@....com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Cc: Roman Li <roman.li@....com>
Cc: Alex Hung <alex.hung@....com>
Cc: Aurabindo Pillai <aurabindo.pillai@....com>
Cc: Harry Wentland <harry.wentland@....com>
Co-developed-by: Alex Hung <alex.hung@....com>
Signed-off-by: Alex Hung <alex.hung@....com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@....com>
Reviewed-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 264e67634dcdc..f59cca515fe22 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -8753,7 +8753,8 @@ static void amdgpu_dm_update_cursor(struct drm_plane *plane,
 	    adev->dm.dc->caps.color.dpp.gamma_corr)
 		attributes.attribute_flags.bits.ENABLE_CURSOR_DEGAMMA = 1;
 
-	attributes.pitch = afb->base.pitches[0] / afb->base.format->cpp[0];
+	if (afb)
+		attributes.pitch = afb->base.pitches[0] / afb->base.format->cpp[0];
 
 	if (crtc_state->stream) {
 		if (!dc_stream_set_cursor_attributes(crtc_state->stream,
-- 
2.43.0