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From dea2f95979cc0ba0c36f07b8e9cc709bd1ef1eb4 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <philmd@redhat.com>
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Date: Fri, 17 Jan 2020 12:00:35 +0100
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Subject: [PATCH 1/3] tcp_emu: Fix oob access
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Philippe Mathieu-Daudé <philmd@redhat.com>
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Message-id: <20200117120037.12800-2-philmd@redhat.com>
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Patchwork-id: 93395
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O-Subject: [RHEL-7.7.z qemu-kvm + RHEL-7.8 qemu-kvm + RHEL-7.9 qemu-kvm PATCH v2 1/3] tcp_emu: Fix oob access
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Bugzilla: 1791560
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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From: Samuel Thibault <samuel.thibault@ens-lyon.org>
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The main loop only checks for one available byte, while we sometimes
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need two bytes.
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(cherry picked from libslirp commit 2655fffed7a9e765bcb4701dd876e9dab975f289)
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[PMD: backported with style conflicts,
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      CHANGELOG.md absent in downstream]
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Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 slirp/tcp_subr.c | 7 +++++++
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 1 file changed, 7 insertions(+)
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diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
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index d49a366..70a4c83 100644
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--- a/slirp/tcp_subr.c
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+++ b/slirp/tcp_subr.c
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@@ -837,6 +837,9 @@ tcp_emu(struct socket *so, struct mbuf *m)
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 				break;
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 			 case 5:
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+				if (bptr == m->m_data + m->m_len - 1)
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+					return 1; /* We need two bytes */
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+
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 				/*
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 				 * The difference between versions 1.0 and
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 				 * 2.0 is here. For future versions of
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@@ -852,6 +855,10 @@ tcp_emu(struct socket *so, struct mbuf *m)
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 				/* This is the field containing the port
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 				 * number that RA-player is listening to.
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 				 */
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+
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+				if (bptr == m->m_data + m->m_len - 1)
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+					return 1; /* We need two bytes */
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+
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 				lport = (((u_char*)bptr)[0] << 8)
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 				+ ((u_char *)bptr)[1];
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 				if (lport < 6970)
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-- 
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1.8.3.1
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