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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 154ACC56201 for ; Mon, 9 Nov 2020 13:27:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B22C52083B for ; Mon, 9 Nov 2020 13:27:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="mYxInpRP"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="lft8dUCw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733114AbgKIN15 (ORCPT ); Mon, 9 Nov 2020 08:27:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730936AbgKIN14 (ORCPT ); Mon, 9 Nov 2020 08:27:56 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B23EC0613CF; Mon, 9 Nov 2020 05:27:56 -0800 (PST) From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604928474; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WG3O0Yq9IgUsxM6iHYTRUGMax2Zqkl4t5Ylzk9NgAgU=; b=mYxInpRPGuHUI0BHTCrs04gRm7r7w6hETgwWcsN+y7uaZ2Xh+DDXpeIGNhgbCkdFQWU9+d VvMM+B3njyInQsQQytpUdcMJDBwoW4PvqaHY1YRaPSBP2oWHn766+uMaJEpmYQj52WMCor e0DX9D8folQLx/G8YmNu+BpcYgy7m+2OEXZ+jZCrjgoo497DCOFnY7Q8ygtvr7yNmZ9Xw0 m3s8OppEtXA0uq/eNmkLSADYw3LC6nt8OEtTtrAwXXl0ua/rzNZjkLgkVl28LIqSY9OTpA mwurtxysrcmaynNcGNhFVHpG2LvQp1yjk6T8EmGaqxSZNuKP9HNoaCXarEZMOw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604928474; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WG3O0Yq9IgUsxM6iHYTRUGMax2Zqkl4t5Ylzk9NgAgU=; b=lft8dUCwRq8EPoK717JI3WT9nSZoDR8fyBgvLKaPF4orIEcjVNfsh8cLB12T9J5Z982NiL Zaewm94tHIcswjDg== To: Colin King , Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S . Miller" , Jakub Kicinski , netdev@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][next] net: dsa: fix unintended sign extension on a u16 left shift In-Reply-To: <20201109124008.2079873-1-colin.king@canonical.com> References: <20201109124008.2079873-1-colin.king@canonical.com> Date: Mon, 09 Nov 2020 14:27:52 +0100 Message-ID: <87y2jar76v.fsf@kurt> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --=-=-= Content-Type: text/plain On Mon Nov 09 2020, Colin King wrote: > From: Colin Ian King > > The left shift of u16 variable high is promoted to the type int and > then sign extended to a 64 bit u64 value. If the top bit of high is > set then the upper 32 bits of the result end up being set by the > sign extension. Fix this by explicitly casting the value in high to > a u64 before left shifting by 16 places. > > Also, remove the initialisation of variable value to 0 at the start > of each loop iteration as the value is never read and hence the > assignment it is redundant. > > Addresses-Coverity: ("Unintended sign extension") > Fixes: e4b27ebc780f ("net: dsa: Add DSA driver for Hirschmann Hellcreek switches") > Signed-off-by: Colin Ian King Reviewed-by: Kurt Kanzenbach --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEooWgvezyxHPhdEojeSpbgcuY8KYFAl+pQ9gACgkQeSpbgcuY 8KYcTBAAy18YsyfEDK2RBP/05cmZJKdrhKGT65m5aI1JezdENk9bCdlxSlc+Oqga rAzG0pQliyooyHkhkk/+uKd0TMFQ5TdbvIW7af2AoAiNADbUrp2I1an/CXbxIBGA kCoyqGmGpmvl6V9/sRklq5Y16BxxhDJVREa4/oeiAl4HEuqUQo/bxnc8bH3puOzx 3SMHt0YZDWLyIAkmocREmMBijzlAlXEpTrIR/QnDJTcAEJgxlUlHwJq8Vn4c+1iR rc2XlsIwzzLz1ah6wfVzP24wbHvFwpGGUMjOR2OubJeKcyn8u5AjqT4z2NCr3/G5 7MhTYblsO0qZVLSxO63ZatXzB8gX+Y6Pr3M6WQqL1B3j4mMrGJSYYohPBHSwKeDh 1z+w8tYNOPGAQ811hjuMrIJh/xGIo4dglYCWASo6oUi611tqrs1WBMaH09E9Dy3F jYj7Zv+K4qMRmeGYLGu3bLihqycZFq3XvyPmGF8aJlKCNAQnPb+2Vk5v5L3AXsSj qD3cJbCO87U86Ee4jYyGnpu/5+g1VGWxQzvzWrtqFyITPJVL1gJ51TEPdG2DvbSb REMVKGPmLZCrylUWmq8zQa7MqCxuI1sSwyIhhAGx/PxvEHc0AlHMm4HNBq8+ZCVD crawO2LX5auQKEudppWsulWZIRQzvO3xaE+3Ov3C85LVvBQ8XWE= =OcYZ -----END PGP SIGNATURE----- --=-=-=--