Fixes CVE-2019-6778:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-6778

Patch copied from upstream source repository:

https://git.qemu.org/?p=qemu.git;a=commitdiff;h=a7104eda7dab99d0cdbd3595c211864cba415905

From a7104eda7dab99d0cdbd3595c211864cba415905 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Sun, 13 Jan 2019 23:29:48 +0530
Subject: [PATCH] slirp: check data length while emulating ident function

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>
---
 slirp/tcp_subr.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index 4a9a5b5edc..23a841f26e 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -634,6 +634,11 @@ 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;
-- 
2.20.1

?id=38fa99c1d09323dff6962489b33f00f765d9b66f'>tree</a><a href='/guix/commit/tests/services/configuration.scm?id=38fa99c1d09323dff6962489b33f00f765d9b66f'>commit</a><a href='/guix/diff/tests/services/configuration.scm?id=38fa99c1d09323dff6962489b33f00f765d9b66f'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/services/configuration.scm'>
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<div class='path'>path: <a href='/guix/log/?id=38fa99c1d09323dff6962489b33f00f765d9b66f&amp;showmsg=1'>root</a>/<a href='/guix/log/tests?id=38fa99c1d09323dff6962489b33f00f765d9b66f&amp;showmsg=1'>tests</a>/<a href='/guix/log/tests/services?id=38fa99c1d09323dff6962489b33f00f765d9b66f&amp;showmsg=1'>services</a>/<a href='/guix/log/tests/services/configuration.scm?id=38fa99c1d09323dff6962489b33f00f765d9b66f&amp;showmsg=1'>configuration.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/services/configuration.scm?id=38fa99c1d09323dff6962489b33f00f765d9b66f'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2021-05-17 23:27:39 -0400'>2021-05-17</span></td><td class='logsubject'><a href='/guix/commit/tests/services/configuration.scm?id=b7297d66c58b4fe2c153dce4f1069235269cd005'>services: configuration: Add a define-maybe/no-serialization syntax.</a></td><td>Maxim Cournoyer</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
Before this change, using define-maybe along define-configuration with the
no-serialization syntactic keyword would result in the following warning:

  warning: possibly unbound variable `VARIABLE-NAME'

This change introduces the define-maybe/no-serialization variant that does
away with defining a serialization helper procedure, which makes it possible
to avoid the above warning.

* gnu/services/configuration.scm (define-maybe/no-serialization): New syntax.
(define-maybe-helper): New procedure.
(define-maybe): Define syntax using the above procedure.
* tests/services/configuration.scm (tests): Fix module name.
(custom-number-serializer): Do not print to standard output.
(maybe-number?, serialize-maybe-number): New procedures defined via the
define-maybe macro.
(config-with-maybe-number): New configuration.
(serialize-number): New procedure.
("maybe value serialization"): New test.
(maybe-string?): New procedure defined via the define-maybe/no-serialization
macro.
(config-with-maybe-string/no-serialization): New configuration.
("maybe value without serialization no procedure bound"): New test.


</td></tr>
<tr class='logheader'><td><span title='2021-05-08 01:04:31 -0400'>2021-05-08</span></td><td class='logsubject'><a href='/guix/commit/tests/services/configuration.scm?id=a77e3a5846d8b4b4b8d0fe4887d1ee17340971e0'>services: configuration: Add tests.</a></td><td>Maxim Cournoyer</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* tests/services/configuration.scm: New file.
* Makefile.am (SCM_TESTS): Register it.


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