V4L/DVB: uvcvideo: Don't use stack-based buffers for USB transfers

Data buffers on the stack are not allowed for USB I/O. Use dynamically
allocated buffers instead when querying control length and control
capabilities.

The control capabilities are now also stored in the uvc_control
structure.

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

3 files changed, 38 insertions, 19 deletions

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index fa06cf512ec..a350fad0db4 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -643,7 +643,7 @@ static struct uvc_control_mapping uvc_ctrl_mappings[] = {
 
 static inline __u8 *uvc_ctrl_data(struct uvc_control *ctrl, int id)
 {
-        return ctrl->data + id * ctrl->info->size;
+        return ctrl->uvc_data + id * ctrl->info->size;
 }
 
 static inline int uvc_test_bit(const __u8 *data, int bit)
@@ -1293,13 +1293,15 @@ int uvc_ctrl_resume_device(struct uvc_device *dev)
  * Control and mapping handling
  */
 
-static void uvc_ctrl_add_ctrl(struct uvc_device *dev,
+static int uvc_ctrl_add_ctrl(struct uvc_device *dev,
         struct uvc_control_info *info)
 {
         struct uvc_entity *entity;
         struct uvc_control *ctrl = NULL;
-        int ret, found = 0;
+        int ret = 0, found = 0;
         unsigned int i;
+        u8 *uvc_info;
+        u8 *uvc_data;
 
         list_for_each_entry(entity, &dev->entities, list) {
                 if (!uvc_entity_match_guid(entity, info->entity))
@@ -1318,56 +1320,69 @@ static void uvc_ctrl_add_ctrl(struct uvc_device *dev,
         }
 
         if (!found)
-                return;
+                return 0;
+
+        uvc_data = kmalloc(info->size * UVC_CTRL_DATA_LAST + 1, GFP_KERNEL);
+        if (uvc_data == NULL)
+                return -ENOMEM;
+
+        uvc_info = uvc_data + info->size * UVC_CTRL_DATA_LAST;
 
         if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT) {
                 /* Check if the device control information and length match
                  * the user supplied information.
                  */
-                __le16 size;
-                __u8 _info;
-
                 ret = uvc_query_ctrl(dev, UVC_GET_LEN, ctrl->entity->id,
-                        dev->intfnum, info->selector, (__u8 *)&size, 2);
+                                     dev->intfnum, info->selector, uvc_data, 2);
                 if (ret < 0) {
                         uvc_trace(UVC_TRACE_CONTROL,
                                 "GET_LEN failed on control %pUl/%u (%d).\n",
                                 info->entity, info->selector, ret);
-                        return;
+                        goto done;
                 }
 
-                if (info->size != le16_to_cpu(size)) {
+                if (info->size != le16_to_cpu(*(__le16 *)uvc_data)) {
                         uvc_trace(UVC_TRACE_CONTROL, "Control %pUl/%u size "
                                 "doesn't match user supplied value.\n",
                                 info->entity, info->selector);
-                        return;
+                        ret = -EINVAL;
+                        goto done;
                 }
 
                 ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id,
-                                     dev->intfnum, info->selector, &_info, 1);
+                                     dev->intfnum, info->selector, uvc_info, 1);
                 if (ret < 0) {
                         uvc_trace(UVC_TRACE_CONTROL,
                                 "GET_INFO failed on control %pUl/%u (%d).\n",
                                 info->entity, info->selector, ret);
-                        return;
+                        goto done;
                 }
 
                 if (((info->flags & UVC_CONTROL_GET_CUR) &&
-                    !(_info & UVC_CONTROL_CAP_GET)) ||
+                    !(*uvc_info & UVC_CONTROL_CAP_GET)) ||
                     ((info->flags & UVC_CONTROL_SET_CUR) &&
-                    !(_info & UVC_CONTROL_CAP_SET))) {
+                    !(*uvc_info & UVC_CONTROL_CAP_SET))) {
                         uvc_trace(UVC_TRACE_CONTROL, "Control %pUl/%u flags "
                                 "don't match supported operations.\n",
                                 info->entity, info->selector);
-                        return;
+                        ret = -EINVAL;
+                        goto done;
                 }
         }
 
         ctrl->info = info;
-        ctrl->data = kmalloc(ctrl->info->size * UVC_CTRL_DATA_LAST, GFP_KERNEL);
+        ctrl->uvc_data = uvc_data;
+        ctrl->uvc_info = uvc_info;
+
         uvc_trace(UVC_TRACE_CONTROL, "Added control %pUl/%u to device %s "
                 "entity %u\n", ctrl->info->entity, ctrl->info->selector,
                 dev->udev->devpath, entity->id);
+
+done:
+        if (ret < 0)
+                kfree(uvc_data);
+
+        return ret;
 }
 
 /*
@@ -1600,7 +1615,7 @@ void uvc_ctrl_cleanup_device(struct uvc_device *dev)
 
         list_for_each_entry(entity, &dev->entities, list) {
                 for (i = 0; i < entity->ncontrols; ++i)
-                        kfree(entity->controls[i].data);
+                        kfree(entity->controls[i].uvc_data);
 
                 kfree(entity->controls);
         }
diff --git a/drivers/media/video/uvc/uvc_v4l2.c b/drivers/media/video/uvc/uvc_v4l2.c
index 485a89912ce..369ce06be03 100644
--- a/drivers/media/video/uvc/uvc_v4l2.c
+++ b/drivers/media/video/uvc/uvc_v4l2.c
@@ -1028,6 +1028,9 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
                 if (!capable(CAP_SYS_ADMIN))
                         return -EPERM;
 
+                if (xinfo->size == 0)
+                        return -EINVAL;
+
                 info = kzalloc(sizeof *info, GFP_KERNEL);
                 if (info == NULL)
                         return -ENOMEM;
diff --git a/drivers/media/video/uvc/uvcvideo.h b/drivers/media/video/uvc/uvcvideo.h
index 14f77e42fd4..47b20e7e378 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -262,7 +262,8 @@ struct uvc_control {
              modified : 1,
              cached : 1;
 
-        __u8 *data;
+        __u8 *uvc_data;
+        __u8 *uvc_info;
 };
 
 struct uvc_format_desc {