Staging: lustre: integer overflow in ioctl

hdr->ioc_len is a user controlled u32 so the addition can overflow,
especially on 32 bit systems.

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

drivers/staging/lustre/lustre/libcfs/linux/linux-module.c

@@ -57,7 +57,7 @@ int libcfs_ioctl_getdata(char *buf, char *end, void *arg)
 		return -EINVAL;
 	}
 
-	if (hdr->ioc_len + buf >= end) {
+	if (hdr->ioc_len >= end - buf) {
 		CERROR("PORTALS: user buffer exceeds kernel buffer\n");
 		return -EINVAL;
 	}