From: "Maciej S. Szmigiero" Subject: Re: [PATCH 2/3] crypto: ccp - return an actual key size from RSA max_size callback Date: Sat, 3 Mar 2018 00:15:20 +0100 Message-ID: <087e7b27-f839-8d4b-8da8-5d0fa2f8caf1@maciej.szmigiero.name> References: <51c265e4-6153-3e5e-316a-ebef059ac36a@maciej.szmigiero.name> <20180302164451.GJ21579@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: "David S. Miller" , David Howells , Tom Lendacky , Gary Hook , keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org To: Herbert Xu Return-path: In-Reply-To: <20180302164451.GJ21579@gondor.apana.org.au> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On 02.03.2018 17:44, Herbert Xu wrote: > On Sat, Feb 24, 2018 at 05:03:21PM +0100, Maciej S. Szmigiero wrote: >> rsa-pkcs1pad uses a value returned from a RSA implementation max_size >> callback as a size of an input buffer passed to the RSA implementation for >> encrypt and sign operations. >> >> CCP RSA implementation uses a hardware input buffer which size depends only >> on the current RSA key length, so it should return this key length in >> the max_size callback, too. >> This also matches what the kernel software RSA implementation does. >> >> Previously, the value returned from this callback was always the maximum >> RSA key size the CCP hardware supports. >> This resulted in this huge buffer being passed by rsa-pkcs1pad to CCP even >> for smaller key sizes and then in a buffer overflow when ccp_run_rsa_cmd() >> tried to copy this large input buffer into a RSA key length-sized hardware >> input buffer. >> >> Signed-off-by: Maciej S. Szmigiero >> Fixes: ceeec0afd684 ("crypto: ccp - Add support for RSA on the CCP") >> Cc: stable@vger.kernel.org > > Patch applied. Thanks. Thanks. However, what about the first patch from this series? Without it, while it no longer should cause a buffer overflow, in-kernel X.509 certificate verification will still fail with CCP driver loaded (since CCP RSA implementation has a higher priority than the software RSA implementation). Maciej