[PATCH v2] media: i2c: alvium: fix critical pointer access in alvium_ctrl_init

[Martin Hecht <mhecht73@gmail.com>]

The current implementation of alvium_ctrl_init creates several controls
in function alvium_ctrl_init and uses the returned pointer without
check. That can cause write access over NULL-pointer for several
controls.
The reworked code checks the pointers before adding flags and also it
creates controls for V4L2_CID_BLUE_BALANCE and V4L2_CID_RED_BALANCE only
if supported by the particular camera model.

Fixes: 0a7af872915e ("media: i2c: Add support for alvium camera")
Cc: stable@vger.kernel.org
Signed-off-by: Martin Hecht <mhecht73@gmail.com>
---
 drivers/media/i2c/alvium-csi2.c | 72 +++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 30 deletions(-)

diff --git a/drivers/media/i2c/alvium-csi2.c b/drivers/media/i2c/alvium-csi2.c
index b62b45a4f2fc..43535ba7a264 100644
--- a/drivers/media/i2c/alvium-csi2.c
+++ b/drivers/media/i2c/alvium-csi2.c
@@ -2100,34 +2100,41 @@ static int alvium_ctrl_init(struct alvium_dev *alvium)
 					      V4L2_CID_PIXEL_RATE, 0,
 					      ALVIUM_DEFAULT_PIXEL_RATE_MHZ, 1,
 					      ALVIUM_DEFAULT_PIXEL_RATE_MHZ);
-	ctrls->pixel_rate->flags |= V4L2_CTRL_FLAG_READ_ONLY;
+	if (ctrls->pixel_rate)
+		ctrls->pixel_rate->flags |= V4L2_CTRL_FLAG_READ_ONLY;
 
 	/* Link freq is fixed */
 	ctrls->link_freq = v4l2_ctrl_new_int_menu(hdl, ops,
 						  V4L2_CID_LINK_FREQ,
 						  0, 0, &alvium->link_freq);
-	ctrls->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
-
-	/* Auto/manual white balance */
+	if (ctrls->link_freq)
+		ctrls->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
+
+	/* manual white balance */
+	if (alvium->avail_ft.whiteb) {
+		ctrls->blue_balance = v4l2_ctrl_new_std(hdl, ops,
+							V4L2_CID_BLUE_BALANCE,
+							alvium->min_bbalance,
+							alvium->max_bbalance,
+							alvium->inc_bbalance,
+							alvium->dft_bbalance);
+
+		ctrls->red_balance = v4l2_ctrl_new_std(hdl, ops,
+						       V4L2_CID_RED_BALANCE,
+						       alvium->min_rbalance,
+						       alvium->max_rbalance,
+						       alvium->inc_rbalance,
+						       alvium->dft_rbalance);
+	}
+
+	/* Auto white balance */
 	if (alvium->avail_ft.auto_whiteb) {
 		ctrls->auto_wb = v4l2_ctrl_new_std(hdl, ops,
 						   V4L2_CID_AUTO_WHITE_BALANCE,
 						   0, 1, 1, 1);
-		v4l2_ctrl_auto_cluster(3, &ctrls->auto_wb, 0, false);
-	}
-
-	ctrls->blue_balance = v4l2_ctrl_new_std(hdl, ops,
-						V4L2_CID_BLUE_BALANCE,
-						alvium->min_bbalance,
-						alvium->max_bbalance,
-						alvium->inc_bbalance,
-						alvium->dft_bbalance);
-	ctrls->red_balance = v4l2_ctrl_new_std(hdl, ops,
-					       V4L2_CID_RED_BALANCE,
-					       alvium->min_rbalance,
-					       alvium->max_rbalance,
-					       alvium->inc_rbalance,
-					       alvium->dft_rbalance);
+		if (ctrls->auto_wb)
+			v4l2_ctrl_auto_cluster(3, &ctrls->auto_wb, 0, false);
+	}
 
 	/* Auto/manual exposure */
 	if (alvium->avail_ft.auto_exp) {
@@ -2136,7 +2143,9 @@ static int alvium_ctrl_init(struct alvium_dev *alvium)
 					       V4L2_CID_EXPOSURE_AUTO,
 					       V4L2_EXPOSURE_MANUAL, 0,
 					       V4L2_EXPOSURE_AUTO);
-		v4l2_ctrl_auto_cluster(2, &ctrls->auto_exp, 1, true);
+		if (ctrls->auto_exp)
+			v4l2_ctrl_auto_cluster(2, &ctrls->auto_exp,
+					       V4L2_EXPOSURE_MANUAL, true);
 	}
 
 	ctrls->exposure = v4l2_ctrl_new_std(hdl, ops,
@@ -2145,15 +2154,8 @@ static int alvium_ctrl_init(struct alvium_dev *alvium)
 					    alvium->max_exp,
 					    alvium->inc_exp,
 					    alvium->dft_exp);
-	ctrls->exposure->flags |= V4L2_CTRL_FLAG_VOLATILE;
-
-	/* Auto/manual gain */
-	if (alvium->avail_ft.auto_gain) {
-		ctrls->auto_gain = v4l2_ctrl_new_std(hdl, ops,
-						     V4L2_CID_AUTOGAIN,
-						     0, 1, 1, 1);
-		v4l2_ctrl_auto_cluster(2, &ctrls->auto_gain, 0, true);
-	}
+	if (ctrls->exposure)
+		ctrls->exposure->flags |= V4L2_CTRL_FLAG_VOLATILE;
 
 	if (alvium->avail_ft.gain) {
 		ctrls->gain = v4l2_ctrl_new_std(hdl, ops,
@@ -2162,7 +2164,17 @@ static int alvium_ctrl_init(struct alvium_dev *alvium)
 						alvium->max_gain,
 						alvium->inc_gain,
 						alvium->dft_gain);
-		ctrls->gain->flags |= V4L2_CTRL_FLAG_VOLATILE;
+		if (ctrls->gain)
+			ctrls->gain->flags |= V4L2_CTRL_FLAG_VOLATILE;
+	}
+
+	/* Auto/manual gain */
+	if (alvium->avail_ft.auto_gain) {
+		ctrls->auto_gain = v4l2_ctrl_new_std(hdl, ops,
+						     V4L2_CID_AUTOGAIN,
+						     0, 1, 1, 1);
+		if (ctrls->auto_gain)
+			v4l2_ctrl_auto_cluster(2, &ctrls->auto_gain, 0, true);
 	}
 
 	if (alvium->avail_ft.sat)
-- 
2.43.0