[media] uvcvideo: Fix uvc_query_v4l2_ctrl() and uvc_xu_ctrl_query() locking

Take the ctrl_mutex mutex before touching control information in those
functions.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 39 insertions, 26 deletions

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index 0d310c422412..f169f7736677 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -863,9 +863,15 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
         unsigned int i;
         int ret;
 
+        ret = mutex_lock_interruptible(&chain->ctrl_mutex);
+        if (ret < 0)
+                return -ERESTARTSYS;
+
         ctrl = uvc_find_control(chain, v4l2_ctrl->id, &mapping);
-        if (ctrl == NULL)
-                return -EINVAL;
+        if (ctrl == NULL) {
+                ret = -EINVAL;
+                goto done;
+        }
 
         memset(v4l2_ctrl, 0, sizeof *v4l2_ctrl);
         v4l2_ctrl->id = mapping->id;
@@ -881,7 +887,7 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
         if (!ctrl->cached) {
                 ret = uvc_ctrl_populate_cache(chain, ctrl);
                 if (ret < 0)
-                        return ret;
+                        goto done;
         }
 
         if (ctrl->info.flags & UVC_CONTROL_GET_DEF) {
@@ -903,19 +909,19 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
                         }
                 }
 
-                return 0;
+                goto done;
 
         case V4L2_CTRL_TYPE_BOOLEAN:
                 v4l2_ctrl->minimum = 0;
                 v4l2_ctrl->maximum = 1;
                 v4l2_ctrl->step = 1;
-                return 0;
+                goto done;
 
         case V4L2_CTRL_TYPE_BUTTON:
                 v4l2_ctrl->minimum = 0;
                 v4l2_ctrl->maximum = 0;
                 v4l2_ctrl->step = 0;
-                return 0;
+                goto done;
 
         default:
                 break;
@@ -933,7 +939,9 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
                 v4l2_ctrl->step = mapping->get(mapping, UVC_GET_RES,
                                   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
 
-        return 0;
+done:
+        mutex_unlock(&chain->ctrl_mutex);
+        return ret;
 }
 
 
@@ -1295,6 +1303,7 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
         struct uvc_entity *entity;
         struct uvc_control *ctrl = NULL;
         unsigned int i, found = 0;
+        int restore = 0;
         __u8 *data;
         int ret;
 
@@ -1326,44 +1335,48 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
                 return -EINVAL;
         }
 
+        if (mutex_lock_interruptible(&chain->ctrl_mutex))
+                return -ERESTARTSYS;
+
         ret = uvc_ctrl_init_xu_ctrl(chain->dev, ctrl);
-        if (ret < 0)
-                return -ENOENT;
+        if (ret < 0) {
+                ret = -ENOENT;
+                goto done;
+        }
 
         /* Validate control data size. */
-        if (ctrl->info.size != xctrl->size)
-                return -EINVAL;
+        if (ctrl->info.size != xctrl->size) {
+                ret = -EINVAL;
+                goto done;
+        }
 
         if ((set && !(ctrl->info.flags & UVC_CONTROL_SET_CUR)) ||
-            (!set && !(ctrl->info.flags & UVC_CONTROL_GET_CUR)))
-                return -EINVAL;
-
-        if (mutex_lock_interruptible(&chain->ctrl_mutex))
-                return -ERESTARTSYS;
+            (!set && !(ctrl->info.flags & UVC_CONTROL_GET_CUR))) {
+                ret = -EINVAL;
+                goto done;
+        }
 
         memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
-               xctrl->size);
+               ctrl->info.size);
         data = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT);
+        restore = set;
 
         if (set && copy_from_user(data, xctrl->data, xctrl->size)) {
                 ret = -EFAULT;
-                goto out;
+                goto done;
         }
 
         ret = uvc_query_ctrl(chain->dev, set ? UVC_SET_CUR : UVC_GET_CUR,
                              xctrl->unit, chain->dev->intfnum, xctrl->selector,
                              data, xctrl->size);
         if (ret < 0)
-                goto out;
+                goto done;
 
-        if (!set && copy_to_user(xctrl->data, data, xctrl->size)) {
+        if (!set && copy_to_user(xctrl->data, data, xctrl->size))
                 ret = -EFAULT;
-                goto out;
-        }
-
-out:
-        if (ret)
+done:
+        if (ret && restore)
                 memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
                        uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
                        xctrl->size);
diff --git a/drivers/media/video/uvc/uvcvideo.h b/drivers/media/video/uvc/uvcvideo.h
index 7d67d95de838..d97cf6d6a4f9 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -413,7 +413,7 @@ struct uvc_video_chain {
         struct uvc_entity *processing;          /* Processing unit */
         struct uvc_entity *selector;            /* Selector unit */
 
-        struct mutex ctrl_mutex;
+        struct mutex ctrl_mutex;                /* Protects ctrl.info */
 };
 
 struct uvc_streaming {