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From c7ede54cbd2e2b25385325600958ba0124e31cc0 Mon Sep 17 00:00:00 2001
From: Ralf Haferkamp <rhafer@suse.com>
Date: Fri, 3 Jul 2020 14:51:16 +0200
Subject: [PATCH] Drop bogus IPv6 messages
Drop IPv6 message shorter than what's mentioned in the payload
length header (+ the size of the IPv6 header). They're invalid an could
lead to data leakage in icmp6_send_echoreply().
CVE: CVE-2020-10756
Upstream-Status: Backport
https://gitlab.freedesktop.org/slirp/libslirp/-/commit/c7ede54cbd2e2b25385325600958ba0124e31cc0
[SG: Based on libslirp commit c7ede54cbd2e2b25385325600958ba0124e31cc0 and adjusted context]
Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com>
---
slirp/src/ip6_input.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/slirp/src/ip6_input.c b/slirp/src/ip6_input.c
index d9d2b7e9..0f2b1785 100644
--- a/slirp/src/ip6_input.c
+++ b/slirp/src/ip6_input.c
@@ -49,6 +49,13 @@ void ip6_input(struct mbuf *m)
goto bad;
}
+ // Check if the message size is big enough to hold what's
+ // set in the payload length header. If not this is an invalid
+ // packet
+ if (m->m_len < ntohs(ip6->ip_pl) + sizeof(struct ip6)) {
+ goto bad;
+ }
+
/* check ip_ttl for a correct ICMP reply */
if (ip6->ip_hl == 0) {
icmp6_send_error(m, ICMP6_TIMXCEED, ICMP6_TIMXCEED_INTRANS);
--
2.17.1
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