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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=unavailable 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 EB7FBC4360F for ; Mon, 11 Mar 2019 07:43:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B81A320643 for ; Mon, 11 Mar 2019 07:43:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726897AbfCKHnt (ORCPT ); Mon, 11 Mar 2019 03:43:49 -0400 Received: from mail-vs1-f65.google.com ([209.85.217.65]:44681 "EHLO mail-vs1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725831AbfCKHns (ORCPT ); Mon, 11 Mar 2019 03:43:48 -0400 Received: by mail-vs1-f65.google.com with SMTP id r201so2102144vsc.11; Mon, 11 Mar 2019 00:43:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SHLIhBTc+6VD4TIc1/cTXBl25ruYc+eCqRhvdq/5uD8=; b=QfwgKRRJWFjIw4Gts2GzHoMDio5GzHR7sU1h3SiJ5yMUgFFL5dPL8zGOZPZWWwNAYX 90YFHLAS2VDhbloNDZTOnZ9Yfyb5Ium7sJrfRyN6D4pzanjpPBMUWp9SNjtYbLw24poF W5v/AngcUs75KyEVxgSUxmiLHewlhG0F4xX5WVY4IAUWxSHRXXIP+0GUdDA2eRgCaLbc hQgXKZP0CTUNRecTDnuj0sz439783xxu4k1jWBziCuiBEFRFlZkQydRd3OMwCEtA3Jwb MrgdcCqYK+cbVnJ+sXjbUYd912lk298QsRVnbVwLNVDAJB3Dtg/xhNu2Y4J5lSJTnOCt AsRQ== X-Gm-Message-State: APjAAAVqSO3hAgHNgHexmG4ydJSFyJYkQKdkPKel6XKswZtmZwo7tpi1 U0/VPBltZENeFHO+QtJj0Dd0NMZ/8nq0lAagK28= X-Google-Smtp-Source: APXvYqzLseUMWhuxsOpfeyXgTkFQ93oA3b4wyD248Ahz3f6/377NiCNkj2khzazEer3yBCw67tfzxS8OZo6M4DR4ptc= X-Received: by 2002:a67:7dd1:: with SMTP id y200mr14406599vsc.96.1552290227176; Mon, 11 Mar 2019 00:43:47 -0700 (PDT) MIME-Version: 1.0 References: <20190311070138.24084-1-kjlu@umn.edu> In-Reply-To: <20190311070138.24084-1-kjlu@umn.edu> From: Geert Uytterhoeven Date: Mon, 11 Mar 2019 08:43:35 +0100 Message-ID: Subject: Re: [PATCH] net: renesas: fix a potential NULL pointer dereference To: Kangjie Lu Cc: pakki001@umn.edu, Sergei Shtylyov , "David S. Miller" , Vladimir Zapolskiy , Geert Uytterhoeven , Vladimir Barinov , Chris Brandt , netdev , Linux-Renesas , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kangjie, On Mon, Mar 11, 2019 at 8:01 AM Kangjie Lu wrote: > In case of_get_phy_mode fails, the fix returns NULL to avoid > the NULL pointer dereference. > > Signed-off-by: Kangjie Lu Thanks for your patch! > --- a/drivers/net/ethernet/renesas/sh_eth.c > +++ b/drivers/net/ethernet/renesas/sh_eth.c > @@ -3187,6 +3187,8 @@ static struct sh_eth_plat_data *sh_eth_parse_dt(struct device *dev) > return NULL; > > pdata->phy_interface = of_get_phy_mode(np); > + if (unlikely(!pdata->phy_interface)) > + return NULL; of_get_phy_mode() does not return a pointer, but a phy mode index. Hence zero is a valid value. So I'm wondering where is the potential NULL pointer dereference? Perhaps we do need to check for negative error codes? Or is this already handled later, by {of_,}phy_connect()? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds