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From fa1aaeeab2f10d7f107dd45a2c06e40e71bde1c3 Mon Sep 17 00:00:00 2001
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From: "wexu@redhat.com" <wexu@redhat.com>
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Date: Wed, 21 Dec 2016 06:04:24 +0100
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Subject: [PATCH 3/4] net: check packet payload length
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RH-Author: wexu@redhat.com
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Message-id: <1482300264-29708-2-git-send-email-wexu@redhat.com>
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Patchwork-id: 73088
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O-Subject: [RHEL-7.4/7.3.z qemu-kvm Patch v2] net: check packet payload length
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Bugzilla: 1398218
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Prasad J Pandit <pjp@fedoraproject.org>
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While computing IP checksum, 'net_checksum_calculate' reads
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payload length from the packet. It could exceed the given 'data'
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buffer size. Add a check to avoid it.
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This patch is to fix CVE-2016-2857.
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https://access.redhat.com/security/cve/CVE-2016-2857
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Reported-by: Liu Ling <liuling-it@360.cn>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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(cherry picked from commit 362786f14a753d8a5256ef97d7c10ed576d6572b)
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Signed-off-by: Wei Xu <wexu@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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net/checksum.c | 10 ++++++++--
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1 file changed, 8 insertions(+), 2 deletions(-)
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diff --git a/net/checksum.c b/net/checksum.c
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index 14c0855..0942437 100644
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--- a/net/checksum.c
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+++ b/net/checksum.c
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@@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *data, int length)
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int hlen, plen, proto, csum_offset;
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uint16_t csum;
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+ /* Ensure data has complete L2 & L3 headers. */
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+ if (length < 14 + 20) {
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+ return;
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+ }
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+
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if ((data[14] & 0xf0) != 0x40)
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return; /* not IPv4 */
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hlen = (data[14] & 0x0f) * 4;
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@@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *data, int length)
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return;
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}
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- if (plen < csum_offset+2)
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- return;
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+ if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
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+ return;
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+ }
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data[14+hlen+csum_offset] = 0;
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data[14+hlen+csum_offset+1] = 0;
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--
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1.8.3.1
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