File tcp_emu-Fix-oob-access.patch of Package qemu

From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Wed, 8 Jan 2020 00:58:48 +0100
Subject: tcp_emu: Fix oob access

Git-commit: 2655fffed7a9e765bcb4701dd876e9dab975f289
References: bsc#1161066, CVE2020-7039, bsc#1161066, CVS-2020-7039

The main loop only checks for one available byte, while we sometimes
need two bytes.

Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 src/tcp_subr.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c
index 6cd181c9f2875528adab3f636aec..cedbfb28686604dbb7e8e5b35dd1 100644
--- a/slirp/src/tcp_subr.c
+++ b/slirp/src/tcp_subr.c
@@ -887,6 +887,9 @@ int tcp_emu(struct socket *so, struct mbuf *m)
                 break;
 
             case 5:
+                if (bptr == m->m_data + m->m_len - 1)
+                        return 1; /* We need two bytes */
+
                 /*
                  * The difference between versions 1.0 and
                  * 2.0 is here. For future versions of
@@ -902,6 +905,10 @@ int tcp_emu(struct socket *so, struct mbuf *m)
                 /* This is the field containing the port
                  * number that RA-player is listening to.
                  */
+
+                if (bptr == m->m_data + m->m_len - 1)
+                        return 1; /* We need two bytes */
+
                 lport = (((uint8_t *)bptr)[0] << 8) + ((uint8_t *)bptr)[1];
                 if (lport < 6970)
                     lport += 256; /* don't know why */