From d11b2eb425d2125f67dd8d8e9b11d9be7d6f3f11 Mon Sep 17 00:00:00 2001
From: Paulo Flabiano Smorigo <pfsmorigo@br.ibm.com>
Date: Wed, 5 Feb 2014 09:42:42 -0200
Subject: [PATCH 133/198] trim arp packets with abnormal size

GRUB uses arp request to create the arp response. If the incoming packet
is foobared, GRUB needs to trim the arp response packet before sending it.
---
 grub-core/net/arp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/grub-core/net/arp.c b/grub-core/net/arp.c
index d62d0cc..77581f4 100644
--- a/grub-core/net/arp.c
+++ b/grub-core/net/arp.c
@@ -162,6 +162,12 @@ grub_net_arp_receive (struct grub_net_buff *nb,
     if (grub_net_addr_cmp (&inf->address, &target_addr) == 0
 	&& grub_be_to_cpu16 (arp_header->op) == ARP_REQUEST)
       {
+        if ((nb->tail - nb->data) > 50)
+          {
+            grub_dprintf ("net", "arp packet with abnormal size (%ld bytes).\n",
+                         nb->tail - nb->data);
+            nb->tail = nb->data + 50;
+          }
 	grub_net_link_level_address_t target;
 	/* We've already checked that pln is either 4 or 16.  */
 	char tmp[16];
-- 
2.7.4