File 0182-slirp-use-correct-size-while-emulat.patch of Package qemu.18973

From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Thu, 9 Jan 2020 15:12:28 +0530
Subject: slirp: use correct size while emulating commands

Git-commit: 82ebe9c370a0e2970fb5695aa19aa5214a6a1c80
References: bsc#1161066, CVE-2020-7039, bsc#1163018, CVE-2020-8608

While emulating services in tcp_emu(), it uses 'mbuf' size
'm->m_size' to write commands via snprintf(3). Use M_FREEROOM(m)
size to avoid possible OOB access.

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-Id: <20200109094228.79764-3-ppandit@redhat.com>
[Since porting from a quite different now libslirp, quite a bit changed]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 slirp/tcp_subr.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index 1cb5cbc380492f0f747134623b38..8c4e4c1d0f4fda5072f391d20ad5 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -703,7 +703,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 			n4 =  (laddr & 0xff);
 
 			m->m_len = bptr - m->m_data; /* Adjust length */
-                        m->m_len += snprintf(bptr, m->m_size - m->m_len,
+                        m->m_len += snprintf(bptr, M_FREEROOM(m),
                                              "ORT %d,%d,%d,%d,%d,%d\r\n%s",
                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 			return 1;
@@ -736,7 +736,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 			n4 =  (laddr & 0xff);
 
 			m->m_len = bptr - m->m_data; /* Adjust length */
-			m->m_len += snprintf(bptr, m->m_size - m->m_len,
+			m->m_len += snprintf(bptr, M_FREEROOM(m),
                                              "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
                                              n1, n2, n3, n4, n5, n6, x==7?buff:"");
 
@@ -762,7 +762,7 @@ tcp_emu(struct socket *so, struct mbuf *m)
 		if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
 		    (so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
 		                     htons(lport), SS_FACCEPTONCE)) != NULL)
-                    m->m_len = snprintf(m->m_data, m->m_size, "%d",
+                    m->m_len = snprintf(m->m_data, M_ROOM(m), "%d",
                                         ntohs(so->so_fport)) + 1;
 		return 1;