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=-5.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 50456C35E04 for ; Tue, 25 Feb 2020 18:23:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C21A2082F for ; Tue, 25 Feb 2020 18:23:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lca.pw header.i=@lca.pw header.b="YulCSFeQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731511AbgBYSXK (ORCPT ); Tue, 25 Feb 2020 13:23:10 -0500 Received: from mail-qk1-f195.google.com ([209.85.222.195]:41211 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731421AbgBYSXJ (ORCPT ); Tue, 25 Feb 2020 13:23:09 -0500 Received: by mail-qk1-f195.google.com with SMTP id b5so95520qkh.8 for ; Tue, 25 Feb 2020 10:23:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=Eau5VULTn0g2cg26CZfaFmmdDpyEbl+Poc4gdYHXnvE=; b=YulCSFeQwMWMd8X2Q9XXl+VGM7pLvFqtCdUQkdbz+1V1tZ5Md0EV8VBmid0D2rpFXb 5v5E/Z87tq1N+haOuMyE+wAVn70RX0OD4uFzy3iUq3VjrnzU2VtAcGcVQTJLOT1Yu78b mu4/PrVnkNp7dJod1+77YPtJHhW1syhL5evLUbIQDDE/7w8I9FG13IXd7pt0BQIU3FSC +IZzzpnnx74gBOepkBI+KN95ZimOsO8qWRDOi/qq1cMjhz6yrGqIQapQfugZJHcjZwrI G7C5PkoNfJWyA7Igdf/Y7mDSJBPggt40I98QjKWD9bbuUez/ypWTt62M3clTIihlusFm PgrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=Eau5VULTn0g2cg26CZfaFmmdDpyEbl+Poc4gdYHXnvE=; b=GQkrDpim0d3EqboIkuP//T4wiXjMWJ9I4VWVCCdTnjfqcqLryXgm6YJ2ptI8w+kOXz D1MiYevdr8NAlL4btez6fsBOHtm/Tg/+ETtoPi2BQaCfjg+cHsoAC89QS4e/IV2jZSrc D56VdRY0WgUoKxM1jDpiBcY8dvFqZ7KIj4jPMmmEWEKHz1IR+EyUsMNufIHJfbrpVlV9 9E7/jsYCG7YbmE1Zgqm1y5iFKirXiX05/JvmWJDtyJY7GheoNSw/1hgtJZn/qczDOiXk p3U9ZgGfSN8YHOX0nQItAb5i3EF96Qv3Hm9AMZXfAyfpEfekOquKVNLt6muA88PVvHWN TF9Q== X-Gm-Message-State: APjAAAUgkUa9RMGtOsTlwxCWZlboSM85NwH9rdjceSalLd+UuFEp3J3N taOEuJ6Q/hbuVkJ/1T0GPzoXe2/rDAQ= X-Google-Smtp-Source: APXvYqzHzTEZDBrq6YQ5dMY901YvFpjixaEtZzSwpviQstu+mluVhiT619QbcL/npwlJzojcsA1mtA== X-Received: by 2002:a05:620a:2185:: with SMTP id g5mr159440qka.4.1582654988641; Tue, 25 Feb 2020 10:23:08 -0800 (PST) Received: from dhcp-41-57.bos.redhat.com (nat-pool-bos-t.redhat.com. [66.187.233.206]) by smtp.gmail.com with ESMTPSA id b5sm2938736qkh.58.2020.02.25.10.23.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Feb 2020 10:23:07 -0800 (PST) Message-ID: <1582654986.7365.120.camel@lca.pw> Subject: Re: [PATCH] xfs: fix an undefined behaviour in _da3_path_shift From: Qian Cai To: Christoph Hellwig Cc: darrick.wong@oracle.com, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 25 Feb 2020 13:23:06 -0500 In-Reply-To: <20200225180725.GA29862@infradead.org> References: <1582641477-4011-1-git-send-email-cai@lca.pw> <20200225180725.GA29862@infradead.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2020-02-25 at 10:07 -0800, Christoph Hellwig wrote: > I think we code do this a tad more cleaner, something like: > > diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c > index 875e04f82541..542a4edfcf54 100644 > --- a/fs/xfs/libxfs/xfs_da_btree.c > +++ b/fs/xfs/libxfs/xfs_da_btree.c > @@ -1986,7 +1986,8 @@ xfs_da3_path_shift( > ASSERT(path != NULL); > ASSERT((path->active > 0) && (path->active < XFS_DA_NODE_MAXDEPTH)); > level = (path->active-1) - 1; /* skip bottom layer in path */ > - for (blk = &path->blk[level]; level >= 0; blk--, level--) { > + for ( ; level >= 0; level--) { > + blk = &path->blk[level]; > xfs_da3_node_hdr_from_disk(dp->i_mount, &nodehdr, > blk->bp->b_addr); > Yes, indeed. I'll send a v2 until Darrick is still not convinced that "path->active == 1" could reach here?