[PATCH 6.19 286/781] media: uvcvideo: Fix allocation for small frame sizes

Greg Kroah-Hartman
2026-02-25T01:32:09Z

From: Ricardo Ribalda <ribalda@chromium.org>

[ Upstream commit 40d3ac25c11310bfaa50ed7614846ef75cb69a1e ]

If a frame has size of less or equal than one packet size
uvc_alloc_urb_buffers() is unable to allocate memory for it due to a
off-by-one error.

Fix the off-by-one-error and now that we are at it, make sure that
stream->urb_size has always a valid value when we return from the
function, even when an error happens.

Fixes: efdc8a9585ce ("V4L/DVB (10295): uvcvideo: Retry URB buffers allocation when the system is low on memory.")
Reported-by: Itay Chamiel <itay.chamiel@q.ai>
Closes: https://lore.kernel.org/linux-media/CANiDSCsSoZf2LsCCoWAUbCg6tJT-ypXR1B85aa6rAdMVYr2iBQ@mail.gmail.com/T/#t
Co-developed-by: Itay Chamiel <itay.chamiel@q.ai>
Signed-off-by: Itay Chamiel <itay.chamiel@q.ai>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Itay Chamiel <itay.chamiel@q.ai>
Link: https://patch.msgid.link/20260114-uvc-alloc-urb-v1-1-cedf3fb66711@chromium.org
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/usb/uvc/uvc_video.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 2094e059d7d39..ec76595f3c4be 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1812,7 +1812,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
npackets = UVC_MAX_PACKETS;

/* Retry allocations until one succeed. */
- for (; npackets > 1; npackets /= 2) {
+ for (; npackets > 0; npackets /= 2) {
stream->urb_size = psize * npackets;

for (i = 0; i < UVC_URBS; ++i) {
@@ -1837,6 +1837,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
uvc_dbg(stream->dev, VIDEO,
"Failed to allocate URB buffers (%u bytes per packet)\n",
psize);
+ stream->urb_size = 0;
return 0;
}

--
2.51.0