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An overflow can occur in the EVP_EncryptUpdate function. If an attacker is able to supply very large amounts of input data after a previous call to EVP_EncryptUpdate with a partial block then a length check can overflow resulting in a heap corruption. Following an analysis of all OpenSSL internal usage of the EVP_EncryptUpdate function all usage is one of two forms. The first form is like this: EVP_EncryptInit() EVP_EncryptUpdate() i.e. where the EVP_EncryptUpdate() call is known to be the first called function after an EVP_EncryptInit(), and therefore that specific call must be safe. The second form is where the length passed to EVP_EncryptUpdate() can be seen from the code to be some small value and therefore there is no possibility of an overflow. Since all instances are one of these two forms, I believe that there can be no overflows in internal code due to this problem. It should be noted that EVP_DecryptUpdate() can call EVP_EncryptUpdate() in certain code paths. Also EVP_CipherUpdate() is a synonym for EVP_EncryptUpdate(). Therefore I have checked all instances of these calls too, and came to the same conclusion, i.e. there are no instances in internal usage where an overflow could occur. This could still represent a security issue for end user code that calls this function directly. CVE-2016-2106 Issue reported by Guido Vranken. Reviewed-by: Tim Hudson <tjh@openssl.org> |
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OpenSSL 1.1.0-pre6-dev
Copyright (c) 1998-2016 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
Secure Sockets Layer (SSLv3) and Transport Layer Security (TLS) protocols as
well as a full-strength general purpose cryptographic library. The project is
managed by a worldwide community of volunteers that use the Internet to
communicate, plan, and develop the OpenSSL toolkit and its related
documentation.
OpenSSL is descended from the SSLeay library developed by Eric A. Young
and Tim J. Hudson. The OpenSSL toolkit is licensed under a dual-license (the
OpenSSL license plus the SSLeay license), which means that you are free to
get and use it for commercial and non-commercial purposes as long as you
fulfill the conditions of both licenses.
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
INSTALL.DJGPP DOS platform with DJGPP
INSTALL.WCE Windows CE
SUPPORT
-------
See the OpenSSL website www.openssl.org for details on how to obtain
commercial technical support.
If you have any problems with OpenSSL then please take the following steps
first:
- Download the current snapshot from ftp://ftp.openssl.org/snapshot/
to see if the problem has already been addressed
- Remove ASM versions of libraries
- Remove compiler optimisation flags
If you wish to report a bug then please include the following information in
any bug report:
- On Unix systems:
Self-test report generated by 'make report'
- On other systems:
OpenSSL version: output of 'openssl version -a'
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)
Email the report to:
rt@openssl.org
In order to avoid spam, this is a moderated mailing list, and it might
take a day for the ticket to show up. (We also scan posts to make sure
that security disclosures aren't publically posted by mistake.) Mail
to this address is recorded in the public RT (request tracker) database
(see https://www.openssl.org/community/index.html#bugs for details) and
also forwarded the public openssl-dev mailing list. Confidential mail
may be sent to openssl-security@openssl.org (PGP key available from the
key servers).
Please do NOT use this for general assistance or support queries.
Just because something doesn't work the way you expect does not mean it
is necessarily a bug in OpenSSL.
You can also make GitHub pull requests. If you do this, please also send
mail to rt@openssl.org with a link to the PR so that we can more easily
keep track of it.
HOW TO CONTRIBUTE TO OpenSSL
----------------------------
See CONTRIBUTING
LEGALITIES
----------
A number of nations, in particular the U.S., 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.