Staging: rspiusb: Fix buffer overflow

usb_buffer_map_sg() may return -1. This will result in a read from
pdx->PixelUrb[frameInfo][-1]

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/staging/rspiusb/rspiusb.c b/drivers/staging/rspiusb/rspiusb.c
index 2f8155c1968b..04e2f92c0f62 100644
--- a/drivers/staging/rspiusb/rspiusb.c
+++ b/drivers/staging/rspiusb/rspiusb.c
@@ -716,6 +716,8 @@ static int MapUserBuffer(struct ioctl_struct *io, struct device_extension *pdx)
                 pdx->PixelUrb[frameInfo][i]->transfer_flags =
                     URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT;
         }
+        if (i == 0)
+                return -EINVAL;
         /* only interrupt when last URB completes */
         pdx->PixelUrb[frameInfo][--i]->transfer_flags &= ~URB_NO_INTERRUPT;
         pdx->pendedPixelUrbs[frameInfo] =