TLS/SSL and crypto library
576129cd72
Thanks to David Benjamin who reported this, performed the analysis and suggested the patch. I have incorporated some of his analysis in the comments below. This issue can cause an out-of-bounds read. It is believed that this was not reachable until the recent "fixed top" changes. Analysis has so far only identified one code path that can encounter this - although it is possible that others may be found. The one code path only impacts 1.0.2 in certain builds. The fuzzer found a path in RSA where iqmp is too large. If the input is all zeros, the RSA CRT logic will multiply a padded zero by iqmp. Two mitigating factors: - Private keys which trip this are invalid (iqmp is not reduced mod p). Only systems which take untrusted private keys care. - In OpenSSL 1.1.x, there is a check which rejects the oversize iqmp, so the bug is only reproducible in 1.0.2 so far. Fortunately, the bug appears to be relatively harmless. The consequences of bn_cmp_word's misbehavior are: - OpenSSL may crash if the buffers are page-aligned and the previous page is non-existent. - OpenSSL will incorrectly treat two BN_ULONG buffers as not equal when they are equal. - Side channel concerns. The first is indeed a concern and is a DoS bug. The second is fine in this context. bn_cmp_word and bn_cmp_part_words are used to compute abs(a0 - a1) in Karatsuba. If a0 = a1, it does not matter whether we use a0 - a1 or a1 - a0. The third would be worth thinking about, but it is overshadowed by the entire Karatsuba implementation not being constant time. Due to the difficulty of tripping this and the low impact no CVE is felt necessary for this issue. Reviewed-by: Paul Dale <paul.dale@oracle.com> Reviewed-by: Viktor Dukhovni <viktor@openssl.org> (Merged from https://github.com/openssl/openssl/pull/8326) |
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OpenSSL 3.0.0-dev
Copyright (c) 1998-2018 The OpenSSL Project
Copyright (c) 1995-1998 Eric A. Young, Tim J. Hudson
All rights reserved.
DESCRIPTION
-----------
The OpenSSL Project is a collaborative effort to develop a robust,
commercial-grade, fully featured, and Open Source toolkit implementing the
Transport Layer Security (TLS) protocols (including SSLv3) as well as a
full-strength general purpose cryptographic library.
OpenSSL is descended from the SSLeay library developed by Eric A. Young
and Tim J. Hudson.
The OpenSSL toolkit is licensed under the Apache License 2.0, which means
that you are free to get and use it for commercial and non-commercial
purposes as long as you fulfill its conditions.
OVERVIEW
--------
The OpenSSL toolkit includes:
libssl (with platform specific naming):
Provides the client and server-side implementations for SSLv3 and TLS.
libcrypto (with platform specific naming):
Provides general cryptographic and X.509 support needed by SSL/TLS but
not logically part of it.
openssl:
A command line tool that can be used for:
Creation of key parameters
Creation of X.509 certificates, CSRs and CRLs
Calculation of message digests
Encryption and decryption
SSL/TLS client and server tests
Handling of S/MIME signed or encrypted mail
And more...
INSTALLATION
------------
See the appropriate file:
INSTALL Linux, Unix, Windows, OpenVMS, ...
NOTES.* INSTALL addendums for different platforms
SUPPORT
-------
See the OpenSSL website www.openssl.org for details on how to obtain
commercial technical support. Free community support is available through the
openssl-users email list (see
https://www.openssl.org/community/mailinglists.html for further details).
If you have any problems with OpenSSL then please take the following steps
first:
- Download the latest version from the repository
to see if the problem has already been addressed
- Configure with no-asm
- Remove compiler optimization flags
If you wish to report a bug then please include the following information
and create an issue on GitHub:
- OpenSSL version: output of 'openssl version -a'
- Configuration data: output of 'perl configdata.pm --dump'
- OS Name, Version, Hardware platform
- Compiler Details (name, version)
- Application Details (name, version)
- Problem Description (steps that will reproduce the problem, if known)
- Stack Traceback (if the application dumps core)
Just because something doesn't work the way you expect does not mean it
is necessarily a bug in OpenSSL. Use the openssl-users email list for this type
of query.
HOW TO CONTRIBUTE TO OpenSSL
----------------------------
See CONTRIBUTING
LEGALITIES
----------
A number of nations restrict the use or export of cryptography. If you
are potentially subject to such restrictions you should seek competent
professional legal advice before attempting to develop or distribute
cryptographic code.