[PATCH v3] 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.

Fixes: 0a7af872915e ("media: i2c: Add support for alvium camera")
Cc: stable@vger.kernel.org
Signed-off-by: Martin Hecht <mhecht73@gmail.com>
---
Changes in v3 (since v1):
- Split conditional creation of manual WB controls into another patch.
- Limit changes only on checking returned pointer values.
- ctrls->pixel_rate->flags is readonly by default, no need to replicate that.

Changes in v2:
- Has been rewoked completely because file was brocken.
---
 drivers/media/i2c/alvium-csi2.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/media/i2c/alvium-csi2.c b/drivers/media/i2c/alvium-csi2.c
index b62b45a4f2fc..f51f9b987759 100644
--- a/drivers/media/i2c/alvium-csi2.c
+++ b/drivers/media/i2c/alvium-csi2.c
@@ -2100,20 +2100,21 @@ 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;
 
 	/* 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;
+	if (ctrls->link_freq)
+		ctrls->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
 
 	/* Auto/manual 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);
+		if (ctrls->auto_wb)
+			v4l2_ctrl_auto_cluster(3, &ctrls->auto_wb, 0, false);
 	}
 
 	ctrls->blue_balance = v4l2_ctrl_new_std(hdl, ops,
@@ -2122,6 +2123,7 @@ static int alvium_ctrl_init(struct alvium_dev *alvium)
 						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,
@@ -2136,7 +2138,9 @@ 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,
@@ -2145,14 +2149,16 @@ 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;
+	if (ctrls->exposure)
+		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->auto_gain)
+			v4l2_ctrl_auto_cluster(2, &ctrls->auto_gain, 0, true);
 	}
 
 	if (alvium->avail_ft.gain) {
@@ -2162,7 +2168,8 @@ 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;
 	}
 
 	if (alvium->avail_ft.sat)
-- 
2.43.0