[SECURITY PATCH 8/8] commands/usbtest: Ensure string length is sufficient in usb string processing

[Daniel Kiper <daniel.kiper () oracle com>]

From: Jamie <volticks () gmail com>

If descstrp->length is less than 2 this will result in underflow in
"descstrp->length / 2 - 1" math. Let's fix the check to make sure the
value is sufficient.

Signed-off-by: Jamie <volticks () gmail com>
Reviewed-by: Daniel Kiper <daniel.kiper () oracle com>
---
 grub-core/commands/usbtest.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/grub-core/commands/usbtest.c b/grub-core/commands/usbtest.c
index 8ef187a9a..3184ac9af 100644
--- a/grub-core/commands/usbtest.c
+++ b/grub-core/commands/usbtest.c
@@ -90,7 +90,7 @@ grub_usb_get_string (grub_usb_device_t dev, grub_uint8_t index, int langid,
                              0x06, (3 << 8) | index,
                              langid, descstr.length, (char *) descstrp);
 
-  if (descstrp->length == 0)
+  if (descstrp->length < 2)
     {
       grub_free (descstrp);
       *string = grub_strdup ("");
-- 
2.11.0