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From 49fbfce352a678b538113598cba05c48281174a4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>
Date: Wed, 24 Jul 2019 15:53:34 +0100
Subject: [PATCH 09/14] slirp: check sscanf result when emulating ident
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RH-Author: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: <20190724155337.25303-2-philmd@redhat.com>
Patchwork-id: 89675
O-Subject: [RHEL-8.1.0 qemu-kvm PATCH v2 1/4] slirp: check sscanf result when emulating ident
Bugzilla: 1727642
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>

From: William Bowling <will@wbowling.info>

When emulating ident in tcp_emu, if the strchr checks passed but the
sscanf check failed, two uninitialized variables would be copied and
sent in the reply, so move this code inside the if(sscanf()) clause.

Signed-off-by: William Bowling <will@wbowling.info>
Cc: qemu-stable@nongnu.org
Cc: secalert@redhat.com
Message-Id: <1551476756-25749-1-git-send-email-will@wbowling.info>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
(cherry picked from commit d3222975c7d6cda9e25809dea05241188457b113)
Fixes: CVE-2019-9824
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 slirp/tcp_subr.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index 1c7eb28..af1b3eb 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -665,12 +665,12 @@ tcp_emu(struct socket *so, struct mbuf *m)
 							break;
 						}
 					}
+					so_rcv->sb_cc = snprintf(so_rcv->sb_data,
+								 so_rcv->sb_datalen,
+								 "%d,%d\r\n", n1, n2);
+					so_rcv->sb_rptr = so_rcv->sb_data;
+					so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 				}
-                                so_rcv->sb_cc = snprintf(so_rcv->sb_data,
-                                                         so_rcv->sb_datalen,
-                                                         "%d,%d\r\n", n1, n2);
-				so_rcv->sb_rptr = so_rcv->sb_data;
-				so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
 			}
 			m_free(m);
 			return 0;
-- 
1.8.3.1