From patchwork Sun Jan 24 14:28:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 12042437 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23179C433E0 for ; Sun, 24 Jan 2021 14:30:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB9E822795 for ; Sun, 24 Jan 2021 14:30:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725948AbhAXOaF (ORCPT ); Sun, 24 Jan 2021 09:30:05 -0500 Received: from mout.gmx.net ([212.227.17.22]:41489 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725775AbhAXOaE (ORCPT ); Sun, 24 Jan 2021 09:30:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1611498490; bh=pITkN1jgrIZQEV8bcGYzV8N4n5kUC2tLoNrCLsr0djs=; h=X-UI-Sender-Class:Date:From:To:Cc:Subject; b=EkGAPm6/g/3gHakZ8mHi0o40mOBFw1hFH28nZMVoBgiaHBB4VY9KdSEyw3l8a27uB dHkzXuXhMIjcMP6b50qHAYTuAndYQN1pxfT2DYX+lnVyXublaABwDNrggLesYTkb6C mgUTDM18wnlaU/YT6aaqnuAFT9RYTGA4q+TkE1yo= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from ls3530.fritz.box ([92.116.141.229]) by mail.gmx.net (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MybGX-1lvGOC3fQ5-00z1pJ; Sun, 24 Jan 2021 15:28:09 +0100 Date: Sun, 24 Jan 2021 15:28:06 +0100 From: Helge Deller To: Ard Biesheuvel , Douglas Anderson , Herbert Xu , "David S. Miller" , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Cc: linux-parisc@vger.kernel.org Subject: [PATCH] crypto: xor - avoid division by zero crash Message-ID: <20210124142806.GA29180@ls3530.fritz.box> MIME-Version: 1.0 Content-Disposition: inline X-Provags-ID: V03:K1:DqwH9uOTMV7uLE4HrG7t8H7vZ8mnUgJG9TgF8O/uBkVq33Oig7h xA92BwWn9hMlzvR40u/4PSaXykiiAcMal3xCT8PJqgQbWLXf5gWn7qLBaDraDiJkbLJGFIh YE6FaENZ8bIDH5PvdFbmdbAIxU8UnQFQDqwwuUMcnwkBe49QFdVis3a7xRRBysbMHhofwOy 1+kwsUkB8mRx1yzCPiCtg== X-UI-Out-Filterresults: notjunk:1;V03:K0:fTdOwco2k5w=:fuG85PIE8hH1F8oVJHqoKf GgBteGdexlWiw+Rdq1rItp47ncCO+31vJJwPjJzR6TdVtGvxkJNg7htcyv7eGCSA6deNCH/TA xflnjxOhkL1eNrHoTV9FBU655PDVIu2XGO0zjZ43IOEvs6JQHk5UNcueseH4lBo0y4gGIVy7n sS6gepmmYssXxWtLkzC/whchTB7Ni4K6hx3aQ7XS92j/U3As/rqcGVJ3VPE+quyQZvoiz9V5j HfRYBkK/neOz2idJknVEqQdFOpDeVDKXas+7tR+PS9VBrkbdXvVlBiEaxD955loIDnpDhikyb kcbr7QMfuQWN5ojl9Squ4vFyU7aqsHC2Rx7cm7N5uY/EJ8rk2PK0EUDfkiZtuUPUEgHW5ZR15 d9k+hsVy6UXw9MOnp+3G1E9XIRgcXON70LBemmg+FHcbJ7QDAmDybgEG4lJpNAd/pk18/D1hy IciEQk4UDQh8h81tdaSOw7kjV0QPYSkgeFFNMSwiLw8l5uIJlxhs7GK/AS9l4mtGV4i7iR1Lv 6RlaMpGvAt3AHHmV/mTsOeUXeFXwGcRv0wl4PeZrEnFDyV2Ys6VCi/BiqxdOssp9RTo2xHV5t RrnnGfBy9N+6wkNHu0FXTmDSitf0lOcEZo8ToG2PYZI3sVaEVDys2Z6d5DN1PKBto9R72bvhV 4gHcUIPjw9AFl+dx6g1LDy8u16H/b/tWxMkCDQsWN4W7Ee1h3oc39HInA1NuUMuH2VjotmQiZ 31KW/20QrNGfFSL72KLR1RlnvwN1CksHTJLQEXNjyGQLsRtgUBN04CLTlTTBEv09PjKLrUCvA vtRVb4wcUC9Oa10jSPujlzjbpByasIGRA4HPsB/T+oBI2E2fzUQhvuifiS/cg3csDmuDbPSx2 Pkm+R202HWQ14/N2NpQg== Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On some of my parisc machines, this patch c055e3eae0f1 ("crypto: xor - use ktime for template benchmarking") triggers a dividy-by-zero exception because "min" becomes zero, which then leads to a kernel crash. It's not clear yet, why I see the issue only on some machines. At least on those the measured time to run the xor speed tests becomes zero nanoseconds. Maybe it's because gcc-10 optimizes the speed test out, or because of some other changes in the time keeping routines. In either case, the kernel should not crash. This patch adds a workaround by reporting such cases with a kernel warning and continues as if the xor tests would have run in 1 ns. Signed-off-by: Helge Deller Cc: stable@vger.kernel.org # 5.10+ diff --git a/crypto/xor.c b/crypto/xor.c index eacbf4f93990..3639341bac7e 100644 --- a/crypto/xor.c +++ b/crypto/xor.c @@ -100,6 +100,8 @@ do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) mb(); } diff = ktime_sub(ktime_get(), start); + if (WARN_ON(diff == 0)) + diff = 1; if (diff < min) min = diff; }