From 30feadb676a0792036a0f64309235c5767e2ee76 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>

Date: Fri, 4 Jun 2021 16:32:55 +0400

Subject: [PATCH 4/7] upd6: check udp6_input buffer size

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Fixes: CVE-2021-3593

Fixes: https://gitlab.freedesktop.org/slirp/libslirp/-/issues/45

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

(cherry picked from commit de71c15de66ba9350bf62c45b05f8fbff166517b)

---

 src/udp6.c | 5 ++++-

 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/udp6.c b/src/udp6.c

index fdd8089..236b962 100644

--- a/src/udp6.c

+++ b/src/udp6.c

@@ -29,7 +29,10 @@ 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;

-- 

2.29.0