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From: Eric Biggers <ebiggers3@gmail.com>
To: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: linux-crypto@vger.kernel.org,
	Herbert Xu <herbert@gondor.apana.org.au>,
	keyrings@vger.kernel.org,
	Mat Martineau <mathew.j.martineau@linux.intel.com>,
	Salvatore Benedetto <salvatore.benedetto@intel.com>,
	Stephan Mueller <smueller@chronox.de>,
	Eric Biggers <ebiggers@google.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH 2/4] crypto: dh - don't permit 'p' to be 0
Date: Thu, 2 Nov 2017 10:31:41 -0700	[thread overview]
Message-ID: <20171102173141.GB23035@gmail.com> (raw)
In-Reply-To: <281c8d97-7d44-d157-5221-1487ec03a06f@microchip.com>

On Thu, Nov 02, 2017 at 01:40:51PM +0200, Tudor Ambarus wrote:
> Hi, Eric,
> 
> On 11/02/2017 12:25 AM, Eric Biggers wrote:
> >If 'p' is 0 for the software Diffie-Hellman implementation, then
> >dh_max_size() returns 0.
> 
> dh_set_secret() returns -EINVAL if p_len < 1536, see
> dh_check_params_length(). What am I missing?
> 
> Cheers,
> ta

You pass a buffer containing 0's, not a buffer of length 0.  The buffer is
interpreted as an arbitrary precision integer, so any length buffer filled with
0's has the mathematical value 0.

Eric

  reply	other threads:[~2017-11-02 17:31 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-01 22:25 [PATCH 0/4] crypto: dh - input validation fixes Eric Biggers
2017-11-01 22:25 ` [PATCH 1/4] crypto: dh - fix double free of ctx->p Eric Biggers
2017-11-02 10:55   ` Tudor Ambarus
2017-11-02 17:30     ` Eric Biggers
2017-11-01 22:25 ` [PATCH 2/4] crypto: dh - don't permit 'p' to be 0 Eric Biggers
2017-11-02 11:40   ` Tudor Ambarus
2017-11-02 17:31     ` Eric Biggers [this message]
2017-11-03  6:23   ` Tudor Ambarus
2017-11-01 22:25 ` [PATCH 3/4] crypto: qat - fix double free of ctx->p Eric Biggers
2017-11-02 17:34   ` Eric Biggers
2017-11-01 22:25 ` [PATCH 4/4] crypto: dh - don't permit 'key' or 'g' size longer than 'p' Eric Biggers

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