USB: usbtest: prevent a divide by zero bug

If param->length is zero, then this could lead to a divide by zero bug
later in the function when we do: size %= max;

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
index f10bd970d50a..7667b12f2ff5 100644
--- a/drivers/usb/misc/usbtest.c
+++ b/drivers/usb/misc/usbtest.c
@@ -423,6 +423,9 @@ alloc_sglist(int nents, int max, int vary)
         unsigned                i;
         unsigned                size = max;
 
+        if (max == 0)
+                return NULL;
+
         sg = kmalloc_array(nents, sizeof *sg, GFP_KERNEL);
         if (!sg)
                 return NULL;