File 0245-slirp-check-len-against-dhcp-option.patch of Package qemu-linux-user.15026

From c4360e1fcc517f796235b405d7f6d91a1688d80b Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Mon, 17 Jul 2017 17:33:26 +0530
Subject: [PATCH] slirp: check len against dhcp options array end

While parsing dhcp options string in 'dhcp_decode', if an options'
length 'len' appeared towards the end of 'bp_vend' array, ensuing
read could lead to an OOB memory access issue. Add check to avoid it.

This is CVE-2017-11434.

Reported-by: Reno Robert <renorobert@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
(cherry picked from commit 413d463f43fbc4dd3a601e80a5724aa384a265a0)
[FL: BSC#1049381 CVE-2017-11434]
Signed-off-by: Fei Li <fli@suse.com>
---
 slirp/bootp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/slirp/bootp.c b/slirp/bootp.c
index 7b3232bdc4..f0508d90d1 100644
--- a/slirp/bootp.c
+++ b/slirp/bootp.c
@@ -123,6 +123,9 @@ static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
             if (p >= p_end)
                 break;
             len = *p++;
+            if (p + len > p_end) {
+                break;
+            }
             DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
 
             switch(tag) {