From: Herbert Xu Subject: Re: unaligned access in pkcs7_verify Date: Mon, 12 Oct 2015 21:32:09 +0800 Message-ID: <20151012133209.GA27746@gondor.apana.org.au> References: <20151002140014.GI18263@oracle.com> <20151008131519.GA24362@gondor.apana.org.au> <20151008144343.GE19655@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dhowells@redhat.com, linux-crypto@vger.kernel.org, "David S. Miller" To: Sowmini Varadhan Return-path: Received: from helcar.hengli.com.au ([209.40.204.226]:39171 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751796AbbJLNcS (ORCPT ); Mon, 12 Oct 2015 09:32:18 -0400 Content-Disposition: inline In-Reply-To: <20151008144343.GE19655@oracle.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, Oct 08, 2015 at 10:43:43AM -0400, Sowmini Varadhan wrote: > On (10/08/15 21:15), Herbert Xu wrote: > > > desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); > > > - sinfo->sig.digest_size = digest_size = crypto_shash_digestsize(tfm); > > > + sinfo->sig.digest_size = digest_size = > > > + ALIGN(crypto_shash_digestsize(tfm), sizeof (*desc)); > : > > What hash algorithm were you using? > > Algorithm is sha1. From printk, crypto_shash_descsize(tfm) comes out > to 0x60, digest_size to 0x14. Stack trace (for each modprobe [-r]) is > > pkcs7_verify+0x1d0/0x5e0 > system_verify_data+0x54/0xb4 > mod_verify_sig+0xa0/0xc4 > load_module+0x48/0x16a0 > SyS_init_module+0x114/0x128 > linux_sparc_syscall+0x34/0x44 Thanks. We have two bugs here. First of all pkcs7_verify definitely shouldn't place the structure after the digest without aligning the pointer. So something like your patch is needed (but please use alignof instead of sizeof). Also don't put in digest_size but instead align the pointer like desc = PTR_ALIGN(digest + digest_size, ...) The sparc sha algorithms themselves need to declare the alignment that they require. Currently they claim to be able to handle any alignment which appears to not be the case. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt