[PATCH] media: v4l: Fix dereference before NULL check

Chandra Mohan Sundar
2025-08-18T09:32:08Z

In 'stm32_csi_start', 'csidev->s_subdev' is dereferenced directly while
assigning a value to the 'src_pad'. However the same value is being
checked against NULL at a later point of time indicating that there
are chances that the value can be NULL.

Move the dereference after the NULL check.

Fixes: e7bad98c205d1 ("media: v4l: Convert the users of v4l2_get_link_freq to call it on a pad")
Signed-off-by: Chandra Mohan Sundar <chandramohan.explore@gmail.com>
---
drivers/media/platform/st/stm32/stm32-csi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/st/stm32/stm32-csi.c b/drivers/media/platform/st/stm32/stm32-csi.c
index b69048144cc1..fd2b6dfbd44c 100644
--- a/drivers/media/platform/st/stm32/stm32-csi.c
+++ b/drivers/media/platform/st/stm32/stm32-csi.c
@@ -443,8 +443,7 @@ static void stm32_csi_phy_reg_write(struct stm32_csi_dev *csidev,
static int stm32_csi_start(struct stm32_csi_dev *csidev,
struct v4l2_subdev_state *state)
{
- struct media_pad *src_pad =
- &csidev->s_subdev->entity.pads[csidev->s_subdev_pad_nb];
+ struct media_pad *src_pad;
const struct stm32_csi_mbps_phy_reg *phy_regs = NULL;
struct v4l2_mbus_framefmt *sink_fmt;
const struct stm32_csi_fmts *fmt;
@@ -466,6 +465,7 @@ static int stm32_csi_start(struct stm32_csi_dev *csidev,
if (!csidev->s_subdev)
return -EIO;

+ src_pad = &csidev->s_subdev->entity.pads[csidev->s_subdev_pad_nb];
link_freq = v4l2_get_link_freq(src_pad,
fmt->bpp, 2 * csidev->num_lanes);
if (link_freq < 0)
--
2.43.0