From c894cd80e9b6c7c317da2dbeacf52a34dc5efdbb Mon Sep 17 00:00:00 2001
From: Xiao Wang <jasowang@redhat.com>
Date: Fri, 22 Feb 2019 08:32:02 +0000
Subject: [PATCH] slirp: check data length while emulating ident function
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

RH-Author: Xiao Wang <jasowang@redhat.com>
Message-id: <20190222083202.20283-1-jasowang@redhat.com>
Patchwork-id: 84699
O-Subject: [RHEL8/rhel qemu-kvm PATCH] slirp: check data length while emulating ident function
Bugzilla: 1669069
RH-Acked-by: Jens Freimann <jfreimann@redhat.com>
RH-Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>

From: Prasad J Pandit <pjp@fedoraproject.org>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1669069
Brew Build: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=20325086
Test status: Tested by myself
Branch: rhel8/master-2.12.0

While emulating identification protocol, tcp_emu() does not check
available space in the 'sc_rcv->sb_data' buffer. It could lead to
heap buffer overflow issue. Add check to avoid it.

Reported-by: Kira <864786842@qq.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
(cherry picked from commit a7104eda7dab99d0cdbd3595c211864cba415905)
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 slirp/tcp_subr.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index da0d537..1c7eb28 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -638,6 +638,11 @@ tcp_emu(struct socket *so, struct mbuf *m)
 			socklen_t addrlen = sizeof(struct sockaddr_in);
 			struct sbuf *so_rcv = &so->so_rcv;
 
+			if (m->m_len > so_rcv->sb_datalen
+					- (so_rcv->sb_wptr - so_rcv->sb_data)) {
+			    return 1;
+			}
+
 			memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
 			so_rcv->sb_wptr += m->m_len;
 			so_rcv->sb_rptr += m->m_len;
-- 
1.8.3.1