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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 0E3BFC18E5A for ; Tue, 10 Mar 2020 13:20:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0564208E4 for ; Tue, 10 Mar 2020 13:20:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583846453; bh=+lIJtQNb3GDX3UdUpxWon3y+MZGFtP4kv/JLgQFn/50=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QDLJLGgUBB+z3rdVaYqOO1v0Dge3Hg/5nxwC5qA5xogDMGzgCws9CxqEww4YtgZn7 jX4RGxU3llC8E5qcBc7OTqoYRUaMWPQy0Y2dmWsK2jQOzTsO9kt1BT6Psyq9hZ0p2V Ek/W5iGt9dYEHR1T5KSbCOJ8ZScTBC7ApnKCL9/k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730882AbgCJNGu (ORCPT ); Tue, 10 Mar 2020 09:06:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:52316 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730486AbgCJNGn (ORCPT ); Tue, 10 Mar 2020 09:06:43 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DA2CE20873; Tue, 10 Mar 2020 13:06:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583845603; bh=+lIJtQNb3GDX3UdUpxWon3y+MZGFtP4kv/JLgQFn/50=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CmgQUakaTw4EpnhZnVvGaB53L+Oy7S0qH2GEUG3m5YAd9UzBfqmn5KkiaFySEATuB RNdQPLGERpBCv24UqEkVBmbwRhzGYbArtxS/AfvWvFz+Go5ieM680DeszBb4MBBAbn Px8+hFRi72tEiamckCSmh9U6BE1cP9FldjUY6O/A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Suraj Jitindar Singh , Dan Carpenter , stable@kernel.org, Theodore Tso Subject: [PATCH 4.14 034/126] ext4: potential crash on allocation error in ext4_alloc_flex_bg_array() Date: Tue, 10 Mar 2020 13:40:55 +0100 Message-Id: <20200310124206.579194582@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310124203.704193207@linuxfoundation.org> References: <20200310124203.704193207@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dan Carpenter commit 37b0b6b8b99c0e1c1f11abbe7cf49b6d03795b3f upstream. If sbi->s_flex_groups_allocated is zero and the first allocation fails then this code will crash. The problem is that "i--" will set "i" to -1 but when we compare "i >= sbi->s_flex_groups_allocated" then the -1 is type promoted to unsigned and becomes UINT_MAX. Since UINT_MAX is more than zero, the condition is true so we call kvfree(new_groups[-1]). The loop will carry on freeing invalid memory until it crashes. Fixes: 7c990728b99e ("ext4: fix potential race between s_flex_groups online resizing and access") Reviewed-by: Suraj Jitindar Singh Signed-off-by: Dan Carpenter Cc: stable@kernel.org Link: https://lore.kernel.org/r/20200228092142.7irbc44yaz3by7nb@kili.mountain Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/super.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2238,7 +2238,7 @@ int ext4_alloc_flex_bg_array(struct supe { struct ext4_sb_info *sbi = EXT4_SB(sb); struct flex_groups **old_groups, **new_groups; - int size, i; + int size, i, j; if (!sbi->s_log_groups_per_flex) return 0; @@ -2259,8 +2259,8 @@ int ext4_alloc_flex_bg_array(struct supe sizeof(struct flex_groups)), GFP_KERNEL); if (!new_groups[i]) { - for (i--; i >= sbi->s_flex_groups_allocated; i--) - kvfree(new_groups[i]); + for (j = sbi->s_flex_groups_allocated; j < i; j++) + kvfree(new_groups[j]); kvfree(new_groups); ext4_msg(sb, KERN_ERR, "not enough memory for %d flex groups", size);