From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E30D7C4332F for ; Wed, 6 Apr 2022 00:22:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1587898AbiDFAKo (ORCPT ); Tue, 5 Apr 2022 20:10:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355928AbiDEKWO (ORCPT ); Tue, 5 Apr 2022 06:22:14 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45A0DAA010; Tue, 5 Apr 2022 03:05:29 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C2DE0B81C83; Tue, 5 Apr 2022 10:05:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F958C385A1; Tue, 5 Apr 2022 10:05:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649153126; bh=jLJHdncUYIgkXzg4FNI//hgrXP1ygYahSZ/ZDNplSPI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pmq56trnaWM/ZLl807DnxuOPUx6afykG188YNkm95olR/CmqPAjtY/7JyriasW4Ub Hl+fSA1FM/anTRMb4OcFCJGCYq9Mfe896e3g5vgQFRbQ5gNjpe7IXI+Bh+i6f2xs66 0XS8sA6E+clfZHdwp2OT9pQ/WWzhKzW4va7Wk+6c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Chikunov , Eric Biggers , Herbert Xu Subject: [PATCH 5.10 110/599] crypto: rsa-pkcs1pad - correctly get hash from source scatterlist Date: Tue, 5 Apr 2022 09:26:44 +0200 Message-Id: <20220405070302.109508656@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070258.802373272@linuxfoundation.org> References: <20220405070258.802373272@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Biggers commit e316f7179be22912281ce6331d96d7c121fb2b17 upstream. Commit c7381b012872 ("crypto: akcipher - new verify API for public key algorithms") changed akcipher_alg::verify to take in both the signature and the actual hash and do the signature verification, rather than just return the hash expected by the signature as was the case before. To do this, it implemented a hack where the signature and hash are concatenated with each other in one scatterlist. Obviously, for this to work correctly, akcipher_alg::verify needs to correctly extract the two items from the scatterlist it is given. Unfortunately, it doesn't correctly extract the hash in the case where the signature is longer than the RSA key size, as it assumes that the signature's length is equal to the RSA key size. This causes a prefix of the hash, or even the entire hash, to be taken from the *signature*. (Note, the case of a signature longer than the RSA key size should not be allowed in the first place; a separate patch will fix that.) It is unclear whether the resulting scheme has any useful security properties. Fix this by correctly extracting the hash from the scatterlist. Fixes: c7381b012872 ("crypto: akcipher - new verify API for public key algorithms") Cc: # v5.2+ Reviewed-by: Vitaly Chikunov Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- crypto/rsa-pkcs1pad.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/crypto/rsa-pkcs1pad.c +++ b/crypto/rsa-pkcs1pad.c @@ -495,7 +495,7 @@ static int pkcs1pad_verify_complete(stru sg_nents_for_len(req->src, req->src_len + req->dst_len), req_ctx->out_buf + ctx->key_size, - req->dst_len, ctx->key_size); + req->dst_len, req->src_len); /* Do the actual verification step. */ if (memcmp(req_ctx->out_buf + ctx->key_size, out_buf + pos, req->dst_len) != 0)