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Fix for CVE-2016-0787 

Make sure that there's a conversion done from number of bytes to number of
bits when the internal _libssh2_bn_rand function is called (CVE-2016-0787)
https://www.libssh2.org/adv_20160223.html
This commit is contained in:
Paul Howarth 2016-02-23 11:19:08 +00:00
parent 33cf9702d8
commit 034fe96dbc
2 changed files with 44 additions and 1 deletions
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32
CVE-2016-0787.patch Normal file
View File

@ -0,0 +1,32 @@
From 8a453a7b0f1e667b7369eb73b00843a8decdecc9 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Thu, 11 Feb 2016 13:52:20 +0100
Subject: [PATCH] diffie_hellman_sha256: convert bytes to bits
As otherwise we get far too small numbers.
CVE-2016-0787
---
src/kex.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/kex.c b/src/kex.c
index 6349457..e89b36c 100644
--- a/src/kex.c
+++ b/src/kex.c
@@ -751,11 +751,11 @@ static int diffie_hellman_sha256(LIBSSH2_SESSION *session,
/* Zero the whole thing out */
memset(&exchange_state->req_state, 0, sizeof(packet_require_state_t));
/* Generate x and e */
- _libssh2_bn_rand(exchange_state->x, group_order, 0, -1);
+ _libssh2_bn_rand(exchange_state->x, group_order * 8 - 1, 0, -1);
_libssh2_bn_mod_exp(exchange_state->e, g, exchange_state->x, p,
exchange_state->ctx);
/* Send KEX init */
/* packet_type(1) + String Length(4) + leading 0(1) */
--
2.7.0

13
libssh2.spec
View File

@ -12,13 +12,14 @@
Name: libssh2
Version: 1.5.0
Release: 1%{?dist}
Release: 2%{?dist}
Summary: A library implementing the SSH2 protocol
Group: System Environment/Libraries
License: BSD
URL: http://www.libssh2.org/
Source0: http://libssh2.org/download/libssh2-%{version}.tar.gz
Patch0: libssh2-1.4.2-utf8.patch
Patch2: https://www.libssh2.org/CVE-2016-0787.patch
BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(id -nu)
BuildRequires: openssl-devel
BuildRequires: zlib-devel
@ -72,6 +73,11 @@ sed -i s/4711/47%{?__isa_bits}/ tests/ssh2.{c,sh}
# Make sure things are UTF-8...
%patch0 -p1
# Make sure that there's a conversion done from number of bytes to number of
# bits when the internal _libssh2_bn_rand function is called (CVE-2016-0787)
# https://www.libssh2.org/adv_20160223.html
%patch2 -p1
# Make sshd transition appropriately if building in an SELinux environment
%if !(0%{?fedora} >= 17 || 0%{?rhel} >= 7)
chcon $(/usr/sbin/matchpathcon -n /etc/rc.d/init.d/sshd) tests/ssh2.sh || :
@ -149,6 +155,11 @@ rm -rf %{buildroot}
%{_libdir}/pkgconfig/libssh2.pc
%changelog
* Tue Feb 23 2016 Paul Howarth <paul@city-fan.org> - 1.5.0-2
- Make sure that there's a conversion done from number of bytes to number of
bits when the internal _libssh2_bn_rand function is called (CVE-2016-0787)
https://www.libssh2.org/adv_20160223.html
* Wed Mar 11 2015 Paul Howarth <paul@city-fan.org> - 1.5.0-1
- Update to 1.5.0
- See RELEASE-NOTES for details of bug fixes and enhancements