From 70ddcf214d647fcdc7158d5a4f0fc3b3f7a6caee Mon Sep 17 00:00:00 2001
Message-Id: <70ddcf214d647fcdc7158d5a4f0fc3b3f7a6caee.1361968543.git.minovotn@redhat.com>
From: Vlad Yasevich <vyasevic@redhat.com>
Date: Thu, 14 Feb 2013 21:39:15 +0100
Subject: [PATCH 1/2] e1000: Discard packets that are too long if !SBP and
 !LPE

RH-Author: Vlad Yasevich <vyasevic@redhat.com>
Message-id: <1360877956-21999-2-git-send-email-vyasevic@redhat.com>
Patchwork-id: 48527
O-Subject: [RHEL-5.10 kvm PATCH 1/2] e1000: Discard packets that are too long if !SBP and !LPE
Bugzilla: 910840
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Amos Kong <akong@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Petr Matousek <pmatouse@redhat.com>

From: Michael Contreras <michael@inetric.com>

The e1000_receive function for the e1000 needs to discard packets longer than
1522 bytes if the SBP and LPE flags are disabled. The linux driver assumes
this behavior and allocates memory based on this assumption.

Signed-off-by: Michael Contreras <michael@inetric.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

(manually cherry picked from b0d9ffcd0251161c7c92f94804dcf599dfa3edeb)

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
---
 qemu/hw/e1000.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

Signed-off-by: Michal Novotny <minovotn@redhat.com>
---
 qemu/hw/e1000.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/qemu/hw/e1000.c b/qemu/hw/e1000.c
index cb6c15b..a3feb93 100644
--- a/qemu/hw/e1000.c
+++ b/qemu/hw/e1000.c
@@ -63,6 +63,9 @@ static int debugflags = DBGBIT(TXERR) | DBGBIT(GENERAL);
  */
 enum { E1000_DEVID = E1000_DEV_ID_82540EM };
 
+/* this is the size past which hardware will drop packets when setting LPE=0 */
+#define MAXIMUM_ETHERNET_VLAN_SIZE 1522
+
 /*
  * May need to specify additional MAC-to-PHY entries --
  * Intel's Windows driver refuses to initialize unless they match
@@ -652,6 +655,13 @@ e1000_receive(void *opaque, const uint8_t *buf, int size)
     if (!(s->mac_reg[RCTL] & E1000_RCTL_EN))
         return;
 
+    /* Discard oversized packets if !LPE and !SBP. */
+    if (size > MAXIMUM_ETHERNET_VLAN_SIZE
+        && !(s->mac_reg[RCTL] & E1000_RCTL_LPE)
+        && !(s->mac_reg[RCTL] & E1000_RCTL_SBP)) {
+        return;
+    }
+
     if (!receive_filter(s, buf, size))
         return;
 
-- 
1.7.11.7