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 A3982C3527E for ; Tue, 5 Apr 2022 11:33:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377170AbiDEL2J (ORCPT ); Tue, 5 Apr 2022 07:28:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243285AbiDEIuT (ORCPT ); Tue, 5 Apr 2022 04:50:19 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C90C12AF2; Tue, 5 Apr 2022 01:38:38 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 267C061500; Tue, 5 Apr 2022 08:38:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F80CC385A1; Tue, 5 Apr 2022 08:38:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649147911; bh=wxo5Qgm4ML6MQghSIyIPjrQXgvNxgJgLaqb67pNgPhk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=asGlX5E3gcurU0uTdjDN+GMNKXlfzFTkyDvvmhGdYlr3dmi725HpCmUCrtRv8+sER vxQ9j7FrjBuYjiwU5hVjb8ffzSWK8gvi3gB/4yh9FvyDbPtc6E5LrU2aiYlwWptJVr eQgn2o0L37EigUYBLkxUv29BRwdTeV21biqpsKBQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tadeusz Struk , Vitaly Chikunov , Eric Biggers , Herbert Xu Subject: [PATCH 5.16 0167/1017] crypto: rsa-pkcs1pad - restore signature length check Date: Tue, 5 Apr 2022 09:18:00 +0200 Message-Id: <20220405070359.181100856@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@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 d3481accd974541e6a5d6a1fb588924a3519c36e upstream. RSA PKCS#1 v1.5 signatures are required to be the same length as the RSA key size. RFC8017 specifically requires the verifier to check this (https://datatracker.ietf.org/doc/html/rfc8017#section-8.2.2). Commit a49de377e051 ("crypto: Add hash param to pkcs1pad") changed the kernel to allow longer signatures, but didn't explain this part of the change; it seems to be unrelated to the rest of the commit. Revert this change, since it doesn't appear to be correct. We can be pretty sure that no one is relying on overly-long signatures (which would have to be front-padded with zeroes) being supported, given that they would have been broken since commit c7381b012872 ("crypto: akcipher - new verify API for public key algorithms"). Fixes: a49de377e051 ("crypto: Add hash param to pkcs1pad") Cc: # v4.6+ Cc: Tadeusz Struk Suggested-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 @@ -538,7 +538,7 @@ static int pkcs1pad_verify(struct akciph if (WARN_ON(req->dst) || WARN_ON(!req->dst_len) || - !ctx->key_size || req->src_len < ctx->key_size) + !ctx->key_size || req->src_len != ctx->key_size) return -EINVAL; req_ctx->out_buf = kmalloc(ctx->key_size + req->dst_len, GFP_KERNEL);