From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 19 Oct 2018 10:12:33 +0000 (+0200)
Subject: dhcp6: make sure we have enough space for the DHCP6 option header
X-Git-Tag: v240~474^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4dac5eaba4e419b29c97da38a8b1f82336c2c892;p=thirdparty%2Fsystemd.git

dhcp6: make sure we have enough space for the DHCP6 option header

Fixes a vulnerability originally discovered by Felix Wilhelm from
Google.

CVE-2018-15688
LP: #1795921
https://bugzilla.redhat.com/show_bug.cgi?id=1639067
---

diff --git a/src/libsystemd-network/dhcp6-option.c b/src/libsystemd-network/dhcp6-option.c
index cbd4bc7a2a3..2806415100c 100644
--- a/src/libsystemd-network/dhcp6-option.c
+++ b/src/libsystemd-network/dhcp6-option.c
@@ -106,7 +106,7 @@ int dhcp6_option_append_ia(uint8_t **buf, size_t *buflen, const DHCP6IA *ia) {
                 return -EINVAL;
         }
 
-        if (*buflen < len)
+        if (*buflen < offsetof(DHCP6Option, data) + len)
                 return -ENOBUFS;
 
         ia_hdr = *buf;