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Message-ID: <YMJECjaaoqDWmnPL@pendragon.ideasonboard.com>
Date: Thu, 10 Jun 2021 19:55:38 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Hans Verkuil <hverkuil-cisco@...all.nl>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
tfiga@...omium.org
Subject: Re: [PATCH v9 14/22] media: uvcvideo: Check controls flags before
accessing them
Hi Ricardo,
Thank you for the patch.
On Fri, Mar 26, 2021 at 10:58:32AM +0100, Ricardo Ribalda wrote:
> We can figure out if reading/writing a set of controls can fail without
> accessing them by checking their flags.
>
> This way we can honor the API closer:
>
> If an error is found when validating the list of controls passed with
> VIDIOC_G_EXT_CTRLS, then error_idx shall be set to ctrls->count to
> indicate to userspace that no actual hardware was touched.
>
> Fixes v4l2-compliance:
> Control ioctls (Input 0):
> warn: v4l2-test-controls.cpp(765): g_ext_ctrls(0) invalid error_idx 0
> fail: v4l2-test-controls.cpp(645): invalid error index write only control
> test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL
>
> Reviewed-by: Hans Verkuil <hverkuil-cisco@...all.nl>
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 22 ++++++++++++++++++
> drivers/media/usb/uvc/uvc_v4l2.c | 39 ++++++++++++++++++++++++++++----
> drivers/media/usb/uvc/uvcvideo.h | 2 ++
> 3 files changed, 58 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 929e70dff11a..24fd5afc4e4f 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1046,6 +1046,28 @@ static int uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
> return 0;
> }
>
> +int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> + bool read)
> +{
> + struct uvc_control_mapping *mapping;
> + struct uvc_control *ctrl;
> +
> + if (__uvc_query_v4l2_class(chain, v4l2_id, 0) >= 0)
> + return -EACCES;
> +
> + ctrl = uvc_find_control(chain, v4l2_id, &mapping);
> + if (!ctrl)
> + return -EINVAL;
> +
> + if (!(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) && read)
> + return -EACCES;
> +
> + if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR) && !read)
> + return -EACCES;
> +
> + return 0;
> +}
> +
> static const char *uvc_map_get_name(const struct uvc_control_mapping *map)
> {
> const char *name;
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 28ccaa8b9e42..a3ee1dc003fc 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -991,6 +991,26 @@ static int uvc_ioctl_query_ext_ctrl(struct file *file, void *fh,
> return 0;
> }
>
> +static int uvc_ctrl_check_access(struct uvc_video_chain *chain,
> + struct v4l2_ext_controls *ctrls,
> + unsigned long ioctl)
> +{
> + struct v4l2_ext_control *ctrl = ctrls->controls;
> + unsigned int i;
> + int ret = 0;
> +
> + for (i = 0; i < ctrls->count; ++ctrl, ++i) {
> + ret = uvc_ctrl_is_accessible(chain, ctrl->id,
> + ioctl == VIDIOC_G_EXT_CTRLS);
> + if (ret)
> + break;
> + }
> +
> + ctrls->error_idx = ioctl == VIDIOC_TRY_EXT_CTRLS ? i : ctrls->count;
> +
> + return ret;
> +}
> +
> static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
> struct v4l2_ext_controls *ctrls)
> {
> @@ -1000,6 +1020,10 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
> unsigned int i;
> int ret;
>
> + ret = uvc_ctrl_check_access(chain, ctrls, VIDIOC_G_EXT_CTRLS);
> + if (ret < 0)
> + return ret;
> +
> if (ctrls->which == V4L2_CTRL_WHICH_DEF_VAL) {
> for (i = 0; i < ctrls->count; ++ctrl, ++i) {
> struct v4l2_queryctrl qc = { .id = ctrl->id };
> @@ -1036,13 +1060,17 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
>
> static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
> struct v4l2_ext_controls *ctrls,
> - bool commit)
> + unsigned long ioctl)
> {
> struct v4l2_ext_control *ctrl = ctrls->controls;
> struct uvc_video_chain *chain = handle->chain;
> unsigned int i;
> int ret;
>
> + ret = uvc_ctrl_check_access(chain, ctrls, ioctl);
> + if (ret < 0)
> + return ret;
> +
> ret = uvc_ctrl_begin(chain);
> if (ret < 0)
> return ret;
> @@ -1051,14 +1079,15 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
> ret = uvc_ctrl_set(handle, ctrl);
> if (ret < 0) {
> uvc_ctrl_rollback(handle);
> - ctrls->error_idx = commit ? ctrls->count : i;
> + ctrls->error_idx = ioctl == VIDIOC_S_EXT_CTRLS ?
> + ctrls->count : i;
> return ret;
> }
> }
>
> ctrls->error_idx = 0;
>
> - if (commit)
> + if (ioctl == VIDIOC_S_EXT_CTRLS)
> return uvc_ctrl_commit(handle, ctrls->controls, ctrls->count);
> else
> return uvc_ctrl_rollback(handle);
> @@ -1069,7 +1098,7 @@ static int uvc_ioctl_s_ext_ctrls(struct file *file, void *fh,
> {
> struct uvc_fh *handle = fh;
>
> - return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, true);
> + return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, VIDIOC_S_EXT_CTRLS);
> }
>
> static int uvc_ioctl_try_ext_ctrls(struct file *file, void *fh,
> @@ -1077,7 +1106,7 @@ static int uvc_ioctl_try_ext_ctrls(struct file *file, void *fh,
> {
> struct uvc_fh *handle = fh;
>
> - return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, false);
> + return uvc_ioctl_s_try_ext_ctrls(handle, ctrls, VIDIOC_TRY_EXT_CTRLS);
> }
>
> static int uvc_ioctl_querymenu(struct file *file, void *fh,
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index dc20021f7ee0..9471c342a310 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -902,6 +902,8 @@ static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
>
> int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);
> int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl);
> +int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> + bool read);
>
> int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
> struct uvc_xu_control_query *xqry);
--
Regards,
Laurent Pinchart
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