From c7ede54cbd2e2b25385325600958ba0124e31cc0 Mon Sep 17 00:00:00 2001 From: Ralf Haferkamp 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 --- 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