grub2/0078-trim-arp-packets-with-abnormal-size.patch

From cffad45026af9a05a0509daf593fa87148a3de66 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 078/215] 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 54306e3b16d..d1c69ed2b55 100644
--- a/grub-core/net/arp.c
+++ b/grub-core/net/arp.c
@@ -150,6 +150,12 @@ grub_net_arp_receive (struct grub_net_buff *nb, struct grub_net_card *card,
     if (grub_net_addr_cmp (&inf->address, &target_addr) == 0
 	&& arp_packet->op == grub_cpu_to_be16_compile_time (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;
 	struct grub_net_buff nb_reply;
 	struct arppkt *arp_reply;
-- 
2.15.0