[PATCH] media: uvcvideo: Fix bug in error path of uvc_alloc_urb_buffers

[Ricardo Ribalda]

Recent cleanup introduced a bug in the error path of
uvc_alloc_urb_buffers(). If there is not enough memory for the
allocation the following error will be triggered:

[  739.196672] UBSAN: shift-out-of-bounds in mm/page_alloc.c:1403:22
[  739.196710] shift exponent 52 is too large for 32-bit type 'int'

Resulting in:
[  740.464422] BUG: unable to handle page fault for address: fffffac1c0800000

The reason for the bug is that usb_free_noncoherent is called with an
invalid size (0) instead of the actual size of the urb.

This patch takes care of that.

Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-media/abycbXzYupZpGkvR@hyeyoo/T/#t
Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Fixes: c824345288d1 ("media: uvcvideo: Pass allocation size directly to uvc_alloc_urb_buffer")
Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
 drivers/media/usb/uvc/uvc_video.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 40c76c051da2..f6c8e3223796 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1751,7 +1751,8 @@ static void uvc_video_complete(struct urb *urb)
 /*
  * Free transfer buffers.
  */
-static void uvc_free_urb_buffers(struct uvc_streaming *stream)
+static void uvc_free_urb_buffers(struct uvc_streaming *stream,
+				 unsigned int size)
 {
 	struct usb_device *udev = stream->dev->udev;
 	struct uvc_urb *uvc_urb;
@@ -1760,7 +1761,7 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream)
 		if (!uvc_urb->buffer)
 			continue;
 
-		usb_free_noncoherent(udev, stream->urb_size, uvc_urb->buffer,
+		usb_free_noncoherent(udev, size, uvc_urb->buffer,
 				     uvc_stream_dir(stream), uvc_urb->sgt);
 		uvc_urb->buffer = NULL;
 		uvc_urb->sgt = NULL;
@@ -1820,7 +1821,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
 
 			if (!uvc_alloc_urb_buffer(stream, uvc_urb, urb_size,
 						  gfp_flags)) {
-				uvc_free_urb_buffers(stream);
+				uvc_free_urb_buffers(stream, urb_size);
 				break;
 			}
 
@@ -1868,7 +1869,7 @@ static void uvc_video_stop_transfer(struct uvc_streaming *stream,
 	}
 
 	if (free_buffers)
-		uvc_free_urb_buffers(stream);
+		uvc_free_urb_buffers(stream, stream->urb_size);
 }
 
 /*

---
base-commit: a93a51f42ac354425a252210183c4151d991f75d
change-id: 20260320-uvc-urb-free-error-e73b1db16e21

Best regards,
-- 
Ricardo Ribalda <ribalda@xxxxxxxxxxxx>