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From 362786f14a753d8a5256ef97d7c10ed576d6572b Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Wed, 2 Mar 2016 17:29:58 +0530
Subject: [PATCH] net: check packet payload length
While computing IP checksum, 'net_checksum_calculate' reads
payload length from the packet. It could exceed the given 'data'
buffer size. Add a check to avoid it.
Reported-by: Liu Ling <liuling-it@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Upstream-Status: Backport
CVE: CVE-2016-2857
http://git.qemu.org/?p=qemu.git;a=commit;h=362786f14a753d8a5256ef97d7c10ed576d6572b
Signed-off-by: Armin Kuster <akuster@mvista.com>
---
net/checksum.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
Index: qemu-2.5.0/net/checksum.c
===================================================================
--- qemu-2.5.0.orig/net/checksum.c
+++ qemu-2.5.0/net/checksum.c
@@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *dat
int hlen, plen, proto, csum_offset;
uint16_t csum;
+ /* Ensure data has complete L2 & L3 headers. */
+ if (length < 14 + 20) {
+ return;
+ }
+
if ((data[14] & 0xf0) != 0x40)
return; /* not IPv4 */
hlen = (data[14] & 0x0f) * 4;
@@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *dat
return;
}
- if (plen < csum_offset+2)
- return;
+ if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
+ return;
+ }
data[14+hlen+csum_offset] = 0;
data[14+hlen+csum_offset+1] = 0;
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