From 0f017f39a390d8fa4ae817f45fbf71a0c8332860 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 16:15:14 +0400
Subject: [PATCH 3/7] bootp: check bootp_input buffer size
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes: CVE-2021-3592
Fixes: https://gitlab.freedesktop.org/slirp/libslirp/-/issues/44

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
(cherry picked from commit 2eca0838eee1da96204545e22cdaed860d9d7c6c)
---
 src/bootp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/bootp.c b/src/bootp.c
index e0db8d1..cafa1eb 100644
--- a/src/bootp.c
+++ b/src/bootp.c
@@ -365,9 +365,9 @@ static void bootp_reply(Slirp *slirp,
 
 void bootp_input(struct mbuf *m)
 {
-    struct bootp_t *bp = mtod(m, struct bootp_t *);
+    struct bootp_t *bp = mtod_check(m, sizeof(struct bootp_t));
 
-    if (bp->bp_op == BOOTP_REQUEST) {
+    if (bp && bp->bp_op == BOOTP_REQUEST) {
         bootp_reply(m->slirp, bp, m_end(m));
     }
 }
-- 
2.29.0