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Date:      Wed, 9 Mar 2016 21:39:58 +0100
From:      Dimitry Andric <dim@FreeBSD.org>
To:        Xin Li <delphij@delphij.net>
Cc:        Antoine Brodin <antoine@FreeBSD.org>, Xin LI <delphij@gmail.com>, Mathieu Arnold <mat@freebsd.org>, Jung-Uk Kim <jkim@freebsd.org>, Bryan Drewery <bdrewery@freebsd.org>, Xin LI <delphij@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, svn-src-releng@freebsd.org
Subject:   Re: svn commit: r296465 - in releng/9.3: . crypto/openssl crypto/openssl/apps crypto/openssl/bugs crypto/openssl/crypto crypto/openssl/crypto/aes crypto/openssl/crypto/asn1 crypto/openssl/crypto/bf cry...
Message-ID:  <2E9527A1-C869-48DA-9554-2A96F1735F8C@FreeBSD.org>
In-Reply-To: <56DFEA05.6060501@delphij.net>
References:  <201603071622.u27GMC4a082792@repo.freebsd.org> <9B6D673B7B15CCDC424E97A8@atuin.in.mat.cc> <56DEFD08.6050100@FreeBSD.org> <63FB9E5BBBF224CA12839457@ogg.in.absolight.net> <56DEFDF5.2040500@FreeBSD.org> <1E2DCDEE8775312979CE7D0B@ogg.in.absolight.net> <56DF0234.2090307@FreeBSD.org> <56DF025B.1090706@FreeBSD.org> <DC10EFD5F03DA877503B6C3E@ogg.in.absolight.net> <56DF0550.6000604@FreeBSD.org> <E24637388915226D9A922B8B@atuin.in.mat.cc> <CAGMYy3tfrty-8r-Efzzd56d4AOdV0H%2BParrkUtBWR4f%2B0ZtxWw@mail.gmail.com> <CAALwa8mXg-eE3tZ1R=LAd9nWNAmTkqPmrSaZAmtrQ=u4-=wEeg@mail.gmail.com> <56DFEA05.6060501@delphij.net>

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On 09 Mar 2016, at 10:16, Xin Li <delphij@delphij.net> wrote:
>=20
> FYI -- I can confirm that libcrypto is broken and have a reliable way =
to
> trigger it.
>=20
> So far I was able to narrow down this to this change and here is a
> temporary workaround (which will reintroduce CVE-2016-0702).
>=20
> Cheers,
> <bn-revert.diff>

FWIW, before the workaround I get this from valgrind:

=3D=3D10050=3D=3D Invalid read of size 8
=3D=3D10050=3D=3D    at 0x6BA3438: MOD_EXP_CTIME_COPY_FROM_PREBUF =
(bn_exp.c:585)
=3D=3D10050=3D=3D    by 0x6BA3438: BN_mod_exp_mont_consttime =
(bn_exp.c:760)
=3D=3D10050=3D=3D    by 0x6B84AB7: ??? (dh_key.c:156)
=3D=3D10050=3D=3D    by 0x4E4550B: ssh_dh_gen_key (in =
/usr/lib/private/libssh.so.5)
=3D=3D10050=3D=3D    by 0x42AEBF: kexgex_server (kexgexs.c:115)
=3D=3D10050=3D=3D    by 0x4E545FE: ssh_kex_input_kexinit (in =
/usr/lib/private/libssh.so.5)
=3D=3D10050=3D=3D    by 0x4E54BBE: ssh_dispatch_run (in =
/usr/lib/private/libssh.so.5)
=3D=3D10050=3D=3D    by 0x41085C: do_ssh2_kex (sshd.c:2559)
=3D=3D10050=3D=3D    by 0x41085C: main (sshd.c:2162)
=3D=3D10050=3D=3D  Address 0x2078f3580 is not stack'd, malloc'd or =
(recently) free'd
=3D=3D10050=3D=3D
=3D=3D10050=3D=3D
=3D=3D10050=3D=3D Process terminating with default action of signal 11 =
(SIGSEGV): dumping core
=3D=3D10050=3D=3D  Access not within mapped region at address =
0x2078F3580
=3D=3D10050=3D=3D    at 0x6BA3438: MOD_EXP_CTIME_COPY_FROM_PREBUF =
(bn_exp.c:585)
=3D=3D10050=3D=3D    by 0x6BA3438: BN_mod_exp_mont_consttime =
(bn_exp.c:760)
=3D=3D10050=3D=3D    by 0x6B84AB7: ??? (dh_key.c:156)
=3D=3D10050=3D=3D    by 0x4E4550B: ssh_dh_gen_key (in =
/usr/lib/private/libssh.so.5)
=3D=3D10050=3D=3D    by 0x42AEBF: kexgex_server (kexgexs.c:115)
=3D=3D10050=3D=3D    by 0x4E545FE: ssh_kex_input_kexinit (in =
/usr/lib/private/libssh.so.5)
=3D=3D10050=3D=3D    by 0x4E54BBE: ssh_dispatch_run (in =
/usr/lib/private/libssh.so.5)
=3D=3D10050=3D=3D    by 0x41085C: do_ssh2_kex (sshd.c:2559)
=3D=3D10050=3D=3D    by 0x41085C: main (sshd.c:2162)
=3D=3D10050=3D=3D  If you believe this happened as a result of a stack
=3D=3D10050=3D=3D  overflow in your program's main thread (unlikely but
=3D=3D10050=3D=3D  possible), you can try to increase the size of the
=3D=3D10050=3D=3D  main thread stack using the --main-stacksize=3D flag.
=3D=3D10050=3D=3D  The main thread stack size used in this run was =
16777216.

-Dimitry


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