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Subject[PATCH v10 14/21] media: uvcvideo: Check controls flags before accessing them
Date
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@xs4all.nl>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
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 2cc2ff0d0cae..18c315b52ef5 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1042,6 +1042,28 @@ 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 b044d9455b2c..4aa78591d9b0 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -901,6 +901,8 @@ 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);
--
2.32.0.288.g62a8d224e6-goog
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