[PATCH] media: uvcvideo: Fix OOB read

[PATCH] media: uvcvideo: Fix OOB read

[Ricardo Ribalda]

If the index provided by the user is bigger than 32, we might do an out
of bound read.

CC: stable@kernel.org
Fixes: 40140eda661e ("media: uvcvideo: Implement mask for V4L2_CTRL_TYPE_MENU")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
Avoid reading index >= 31
---
 drivers/media/usb/uvc/uvc_ctrl.c | 3 +++
 drivers/media/usb/uvc/uvcvideo.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 5e9d3da862dd..5e3af66a2223 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1402,6 +1402,9 @@ int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
 	query_menu->id = id;
 	query_menu->index = index;
 
+	if (index >= UVC_MAX_MENU)
+		return -EINVAL;
+
 	ret = mutex_lock_interruptible(&chain->ctrl_mutex);
 	if (ret < 0)
 		return -ERESTARTSYS;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 6fb0a78b1b00..139608f83499 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -101,6 +101,7 @@ struct uvc_control_info {
 	u32 flags;
 };
 
+#define UVC_MAX_MENU 32
 struct uvc_control_mapping {
 	struct list_head list;
 	struct list_head ev_subs;

---
base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c
change-id: 20230717-uvc-oob-4b0148a00417

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>

Re: [PATCH] media: uvcvideo: Fix OOB read

[Sergey Senozhatsky]

On (23/07/19 12:05), Ricardo Ribalda wrote:
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 5e9d3da862dd..5e3af66a2223 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1402,6 +1402,9 @@ int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
>  	query_menu->id = id;
>  	query_menu->index = index;
>  
> +	if (index >= UVC_MAX_MENU)
> +		return -EINVAL;

We probably can just do

	if (index >= BITS_PER_TYPE(mapping->menu_mask))
		return -EINVAL;

This should be better than using a hard-coded constant or even
BITS_PER_LONG (which is still a hard-coded constant). Because
BITS_PER_LONG won't get us covered if one day ->menu_mask data
type changes.