Re: [PATCH v3 2/2] media: ivtv: Fix invalid access to file *

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

Thank you for the patch.

On Mon, Aug 18, 2025 at 10:39:37PM +0200, Jacopo Mondi wrote:
> Since commit 9ba9d11544f9 ("media: ivtv: Access v4l2_fh from file")
> all ioctl handlers have been ported to operate on the file * first
> function argument.
> 
> The ivtv DVB layer calls ivtv_init_on_first_open() when the driver
> needs to start streaming. This function calls the s_input() 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.

You may want to reword this in a similar way as proposed in 1/2.

> 
> The ivtv_do_s_input() helper accepts a struct ivtv * as first argument,
> which is easily accessible from the DVB layer as well as from the file *
> argument of the ioctl handler.
> 
> The ivtv_s_frequency() takes an ivtv_stream * instead. The stream * can
> safely be accessed from the DVB layer which hard-codes it to the
> IVTV_ENC_STREAM_TYPE_MPG stream type, as well as from the ioctl handler
> a valid stream type is associated to each open file handle depending on
> which video device node has been opened in the ivtv_open() file
> operation.
> 
> The bug has been reported by Smatch.
> 
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/all/aKL4OMWsESUdX8KQ@stanley.mountain/
> Fixes: 9ba9d11544f9 ("media: ivtv: Access v4l2_fh from file")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> ---
>  drivers/media/pci/ivtv/ivtv-driver.c | 11 ++++-------
>  drivers/media/pci/ivtv/ivtv-ioctl.c  | 22 +++++++++++++++++-----
>  drivers/media/pci/ivtv/ivtv-ioctl.h  |  6 ++++--
>  3 files changed, 25 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/media/pci/ivtv/ivtv-driver.c b/drivers/media/pci/ivtv/ivtv-driver.c
> index ecc20cd89926fe2ce4e472526a6b5fc0857615dd..7e2fb98cfccf02f701ceb4484dd1d330dd1dc867 100644
> --- a/drivers/media/pci/ivtv/ivtv-driver.c
> +++ b/drivers/media/pci/ivtv/ivtv-driver.c
> @@ -1260,15 +1260,12 @@ static int ivtv_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
>  
>  int ivtv_init_on_first_open(struct ivtv *itv)
>  {
> -	struct v4l2_frequency vf;
>  	/* Needed to call ioctls later */

I'd drop the comment.

> -	struct ivtv_open_id fh;
> +	struct ivtv_stream *s = &itv->streams[IVTV_ENC_STREAM_TYPE_MPG];
> +	struct v4l2_frequency vf;
>  	int fw_retry_count = 3;
>  	int video_input;
>  
> -	fh.itv = itv;
> -	fh.type = IVTV_ENC_STREAM_TYPE_MPG;
> -
>  	if (test_bit(IVTV_F_I_FAILED, &itv->i_flags))
>  		return -ENXIO;
>  
> @@ -1310,13 +1307,13 @@ int ivtv_init_on_first_open(struct ivtv *itv)
>  
>  	video_input = itv->active_input;
>  	itv->active_input++;	/* Force update of input */
> -	ivtv_s_input(NULL, &fh, video_input);
> +	ivtv_do_s_input(itv, video_input);
>  
>  	/* Let the VIDIOC_S_STD ioctl do all the work, keeps the code
>  	   in one place. */
>  	itv->std++;		/* Force full standard initialization */
>  	itv->std_out = itv->std;
> -	ivtv_s_frequency(NULL, &fh, &vf);
> +	ivtv_do_s_frequency(s, &vf);

	ivtv_do_s_frequency(&itv->streams[IVTV_ENC_STREAM_TYPE_MPG], &vf);

would work too. Up to you.

>  
>  	if (itv->card->v4l2_capabilities & V4L2_CAP_VIDEO_OUTPUT) {
>  		/* Turn on the TV-out: ivtv_init_mpeg_decoder() initializes
> diff --git a/drivers/media/pci/ivtv/ivtv-ioctl.c b/drivers/media/pci/ivtv/ivtv-ioctl.c
> index 8077a71d4850ec773caa20c3fca08f92f3117d69..dfbc842b22453868a2075935a81db7ae313ee46c 100644
> --- a/drivers/media/pci/ivtv/ivtv-ioctl.c
> +++ b/drivers/media/pci/ivtv/ivtv-ioctl.c
> @@ -974,9 +974,8 @@ static int ivtv_g_input(struct file *file, void *fh, unsigned int *i)
>  	return 0;
>  }
>  
> -int ivtv_s_input(struct file *file, void *fh, unsigned int inp)
> +int ivtv_do_s_input(struct ivtv *itv, unsigned int inp)
>  {
> -	struct ivtv *itv = file2id(file)->itv;
>  	v4l2_std_id std;
>  	int i;
>  
> @@ -1017,6 +1016,11 @@ int ivtv_s_input(struct file *file, void *fh, unsigned int inp)
>  	return 0;
>  }
>  
> +static int ivtv_s_input(struct file *file, void *fh, unsigned int inp)
> +{
> +	return ivtv_do_s_input(file2id(file)->itv, inp);
> +}
> +
>  static int ivtv_g_output(struct file *file, void *fh, unsigned int *i)
>  {
>  	struct ivtv *itv = file2id(file)->itv;
> @@ -1065,10 +1069,9 @@ static int ivtv_g_frequency(struct file *file, void *fh, struct v4l2_frequency *
>  	return 0;
>  }
>  
> -int ivtv_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *vf)
> +int ivtv_do_s_frequency(struct ivtv_stream *s, const struct v4l2_frequency *vf)
>  {
> -	struct ivtv *itv = file2id(file)->itv;
> -	struct ivtv_stream *s = &itv->streams[file2id(file)->type];
> +	struct ivtv *itv = s->itv;
>  
>  	if (s->vdev.vfl_dir)
>  		return -ENOTTY;
> @@ -1082,6 +1085,15 @@ int ivtv_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *v
>  	return 0;
>  }
>  
> +static int ivtv_s_frequency(struct file *file, void *fh,
> +			    const struct v4l2_frequency *vf)
> +{
> +	struct ivtv_open_id *id = file2id(file);
> +	struct ivtv *itv = id->itv;
> +
> +	return ivtv_do_s_frequency(&itv->streams[id->type], vf);
> +}
> +
>  static int ivtv_g_std(struct file *file, void *fh, v4l2_std_id *std)
>  {
>  	struct ivtv *itv = file2id(file)->itv;
> diff --git a/drivers/media/pci/ivtv/ivtv-ioctl.h b/drivers/media/pci/ivtv/ivtv-ioctl.h
> index 42c2516379fcbbd0640820ab0e3abe9bf00b57ea..dd713a6b095e5ebca45a234dd6c9a90df0928596 100644
> --- a/drivers/media/pci/ivtv/ivtv-ioctl.h
> +++ b/drivers/media/pci/ivtv/ivtv-ioctl.h
> @@ -17,7 +17,9 @@ int ivtv_set_speed(struct ivtv *itv, int speed);
>  void ivtv_set_funcs(struct video_device *vdev);
>  void ivtv_s_std_enc(struct ivtv *itv, v4l2_std_id std);
>  void ivtv_s_std_dec(struct ivtv *itv, v4l2_std_id std);
> -int ivtv_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *vf);
> -int ivtv_s_input(struct file *file, void *fh, unsigned int inp);
> +
> +struct ivtv;

I'd drop this, as the structure is already used above.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

> +int ivtv_do_s_frequency(struct ivtv_stream *s, const struct v4l2_frequency *vf);
> +int ivtv_do_s_input(struct ivtv *itv, unsigned int inp);
>  
>  #endif
> 

-- 
Regards,

Laurent Pinchart