From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754823AbbCMKdR (ORCPT ); Fri, 13 Mar 2015 06:33:17 -0400 Received: from ringil.hengli.com.au ([178.18.16.133]:37954 "EHLO ringil.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751267AbbCMKdO (ORCPT ); Fri, 13 Mar 2015 06:33:14 -0400 Date: Fri, 13 Mar 2015 21:33:06 +1100 From: Herbert Xu To: Stephan Mueller Cc: tadeusz.struk@intel.com, linux-crypto@vger.kernel.org, "'LKML'" Subject: Re: [PATCH v2] crypto: AES-NI - fix memory usage in GCM decryption Message-ID: <20150313103306.GA1559@gondor.apana.org.au> References: <44569470.FQKUtYhtg6@tachyon.chronox.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44569470.FQKUtYhtg6@tachyon.chronox.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 12, 2015 at 09:17:51AM +0100, Stephan Mueller wrote: > The kernel crypto API logic requires the caller to provide the > length of (ciphertext || authentication tag) as cryptlen for the > AEAD decryption operation. Thus, the cipher implementation must > calculate the size of the plaintext output itself and cannot simply use > cryptlen. > > The RFC4106 GCM decryption operation tries to overwrite cryptlen memory > in req->dst. As the destination buffer for decryption only needs to hold > the plaintext memory but cryptlen references the input buffer holding > (ciphertext || authentication tag), the assumption of the destination > buffer length in RFC4106 GCM operation leads to a too large size. This > patch simply uses the already calculated plaintext size. > > In addition, this patch fixes the offset calculation of the AAD buffer > pointer: as mentioned before, cryptlen already includes the size of the > tag. Thus, the tag does not need to be added. With the addition, the AAD > will be written beyond the already allocated buffer. > > Note, this fixes a kernel crash that can be triggered from user space > via AF_ALG(aead) -- simply use the libkcapi test application > from [1] and update it to use rfc4106-gcm-aes. > > Using [1], the changes were tested using CAVS vectors to demonstrate > that the crypto operation still delivers the right results. > > [1] http://www.chronox.de/libkcapi.html > > CC: Tadeusz Struk > Signed-off-by: Stephan Mueller Patch applied. Thanks! -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt