On Mon, Aug 18, 2025 at 02:40:11PM +0200, Jacopo Mondi wrote:

Sice commit 7b9eb53e8591 ("media: cx18: Access v4l2_fh from file") all ioctl handlers have been ported to operate on the file * first function argument.

The cx18 DVB layer calls cx18_init_on_first_open() when the driver needs to start streaming. This function calls the s_input(), s_std() and s_frequency() ioctl handlers directly, but being called from the driver context, it doesn't have a valid file * to pass them. This causes the ioctl handlers to deference an invalid pointer.

Fix this by wrapping the ioctl handlers implementation in helper functions which accepts a cx18_open_id pointer as first argument and make the cx18_init_on_first_open() function call the helpers without going through the ioctl handlers.

The bug has been reported by Smatch:

--> 1223 cx18_s_input(NULL, &fh, video_input); The patch adds a new dereference of "file" but some of the callers pass a NULL pointer.

Reported-by: Dan Carpenter dan.carpenter@linaro.org Closes: https://lore.kernel.org/all/aKL4OMWsESUdX8KQ@stanley.mountain/ Fixes: 7b9eb53e8591 ("media: cx18: Access v4l2_fh from file") Signed-off-by: Jacopo Mondi jacopo.mondi@ideasonboard.com

---

drivers/media/pci/cx18/cx18-driver.c | 6 +++--- drivers/media/pci/cx18/cx18-ioctl.c | 26 ++++++++++++++++++++------ drivers/media/pci/cx18/cx18-ioctl.h | 8 +++++--- 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/drivers/media/pci/cx18/cx18-driver.c b/drivers/media/pci/cx18/cx18-driver.c index 743fcc9613744bfc1edeffc51e908fe88520405a..e1798850ff78a50d7930148622c87d9303033c45 100644 --- a/drivers/media/pci/cx18/cx18-driver.c +++ b/drivers/media/pci/cx18/cx18-driver.c @@ -1220,14 +1220,14 @@ int cx18_init_on_first_open(struct cx18 *cx) video_input = cx->active_input; cx->active_input++; /* Force update of input */

• cx18_s_input(NULL, &fh, video_input);

• cx18_do_s_input(&fh, video_input);

/* Let the VIDIOC_S_STD ioctl do all the work, keeps the code in one place. */ cx->std++; /* Force full standard initialization */ std = (cx->tuner_std == V4L2_STD_ALL) ? V4L2_STD_NTSC_M : cx->tuner_std;

• cx18_s_std(NULL, &fh, std);
• cx18_s_frequency(NULL, &fh, &vf);

• cx18_do_s_std(&fh, std);
• cx18_do_s_frequency(&fh, &vf); return 0;

} diff --git a/drivers/media/pci/cx18/cx18-ioctl.c b/drivers/media/pci/cx18/cx18-ioctl.c index bf16d36448f888d9326b5f4a8f9c8f0e13d0c3a1..507df0d885e0dd2df7446aaef9e066592496d215 100644 --- a/drivers/media/pci/cx18/cx18-ioctl.c +++ b/drivers/media/pci/cx18/cx18-ioctl.c @@ -521,9 +521,8 @@ static int cx18_g_input(struct file *file, void *fh, unsigned int *i) return 0; } -int cx18_s_input(struct file *file, void *fh, unsigned int inp) +int cx18_do_s_input(struct cx18_open_id *id, unsigned int inp)

As id is only used to access id->cx, I would pass a cx18 pointer to this function. Same for cx18_do_s_std() and cx18_do_s_frequency(). This will allow dropping the fake fh variable from cx18_init_on_first_open().

{

• struct cx18_open_id *id = file2id(file); struct cx18 *cx = id->cx; v4l2_std_id std = V4L2_STD_ALL; const struct cx18_card_video_input *card_input =

@@ -558,6 +557,11 @@ int cx18_s_input(struct file *file, void *fh, unsigned int inp) return 0; } +static int cx18_s_input(struct file *file, void *fh, unsigned int inp) +{

• return cx18_do_s_input(file2id(file), inp);

+}

static int cx18_g_frequency(struct file *file, void *fh, struct v4l2_frequency *vf) { @@ -570,9 +574,9 @@ static int cx18_g_frequency(struct file *file, void *fh, return 0; } -int cx18_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *vf) +int cx18_do_s_frequency(struct cx18_open_id *id,

• 	const struct v4l2_frequency *vf)
  

{

• struct cx18_open_id *id = file2id(file); struct cx18 *cx = id->cx;

if (vf->tuner != 0) @@ -585,6 +589,12 @@ int cx18_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *v return 0; } +static int cx18_s_frequency(struct file *file, void *fh,

• 	    const struct v4l2_frequency *vf)
  

+{

• return cx18_do_s_frequency(file2id(file), vf);

+}

static int cx18_g_std(struct file *file, void *fh, v4l2_std_id *std) { struct cx18 *cx = file2id(file)->cx; @@ -593,9 +603,8 @@ static int cx18_g_std(struct file *file, void *fh, v4l2_std_id *std) return 0; } -int cx18_s_std(struct file *file, void *fh, v4l2_std_id std) +int cx18_do_s_std(struct cx18_open_id *id, v4l2_std_id std) {

• struct cx18_open_id *id = file2id(file); struct cx18 *cx = id->cx;

if ((std & V4L2_STD_ALL) == 0) @@ -642,6 +651,11 @@ int cx18_s_std(struct file *file, void *fh, v4l2_std_id std) return 0; } +static int cx18_s_std(struct file *file, void *fh, v4l2_std_id std) +{

• return cx18_do_s_std(file2id(file), std);

+}

static int cx18_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt) { struct cx18_open_id *id = file2id(file); diff --git a/drivers/media/pci/cx18/cx18-ioctl.h b/drivers/media/pci/cx18/cx18-ioctl.h index 221e2400fb3e2d817eaff7515fa89eb94f2d7f8a..bd0e6e5ac4e4a66f747789fd45b1d026c6905601 100644 --- a/drivers/media/pci/cx18/cx18-ioctl.h +++ b/drivers/media/pci/cx18/cx18-ioctl.h @@ -12,6 +12,8 @@ u16 cx18_service2vbi(int type); void cx18_expand_service_set(struct v4l2_sliced_vbi_format *fmt, int is_pal); u16 cx18_get_service_set(struct v4l2_sliced_vbi_format *fmt); void cx18_set_funcs(struct video_device *vdev); -int cx18_s_std(struct file *file, void *fh, v4l2_std_id std); -int cx18_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *vf); -int cx18_s_input(struct file *file, void *fh, unsigned int inp);

+struct cx18_open_id; +int cx18_do_s_std(struct cx18_open_id *id, v4l2_std_id std); +int cx18_do_s_frequency(struct cx18_open_id *id, const struct v4l2_frequency *vf); +int cx18_do_s_input(struct cx18_open_id *id, unsigned int inp);