upd6: check udp6_input buffer size

Git-commit: de71c15de66ba9350bf62c45b05f8fbff166517b
References: bsc#1187365, CVE-2021-3593

Fixes: CVE-2021-3593
Fixes: https://gitlab.freedesktop.org/slirp/libslirp/-/issues/45
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Jose R Ziviani <jose.ziviani@suse.com>

diff --git a/slirp/src/udp6.c b/slirp/src/udp6.c
index 6f9486bbcae904542547c590b0c3f673f8cb5d21..8c490e4d10abecc536ce4405e223cb637d2f19ad 100644 (file)
--- a/slirp/src/udp6.c
+++ b/slirp/src/udp6.c
@@ -28,7 +28,10 @@ void udp6_input(struct mbuf *m)
     ip = mtod(m, struct ip6 *);
     m->m_len -= iphlen;
     m->m_data += iphlen;
-    uh = mtod(m, struct udphdr *);
+    uh = mtod_check(m, sizeof(struct udphdr));
+    if (uh == NULL) {
+        goto bad;
+    }
     m->m_len += iphlen;
     m->m_data -= iphlen;