From patchwork Tue Mar 3 17:42:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 229878 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,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 D6D82C3F2D1 for ; Tue, 3 Mar 2020 18:12:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A89A220838 for ; Tue, 3 Mar 2020 18:12:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583259167; bh=Y3LjSFDNDbB30Lkn3Xht6FHBP7+/4zbis0aasRQLWyA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EHgr+EXYVK503OVxT1nC9NND8iIgPh1+WudqgQJgdAZdJ6pnh3QzM2hF5JENUYolk xUjh8WD5VIuQAGzhd+68l3vGKuqbYk4Ut5G7zb98We7M0FzUMeQB1lUKBsdRXIzwMp ccipPMP+t3vvZtB1GhVnQdqKL/ZJnzdwHrJrdUZU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731434AbgCCRrv (ORCPT ); Tue, 3 Mar 2020 12:47:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:54798 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731418AbgCCRru (ORCPT ); Tue, 3 Mar 2020 12:47:50 -0500 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 68C88208C3; Tue, 3 Mar 2020 17:47:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583257669; bh=Y3LjSFDNDbB30Lkn3Xht6FHBP7+/4zbis0aasRQLWyA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HIxuAnzVgaDtPYhW2kdLVS6dl88kr5yP9iYm60nIgG6Myz2EUVUH/DQ/mce9NVvc9 O93nofxAG2pVnoTAm57/eh1+TMH7BLpGiTe5e+EUWkV4HoEluHi5DFC3pZUKvBOhlw unf2Uy16EPprGwPRxyCcPjXlQ7c3pwQ2E09wrerY= 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 5.5 084/176] ext4: potential crash on allocation error in ext4_alloc_flex_bg_array() Date: Tue, 3 Mar 2020 18:42:28 +0100 Message-Id: <20200303174314.387460316@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200303174304.593872177@linuxfoundation.org> References: <20200303174304.593872177@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 @@ -2346,7 +2346,7 @@ 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; @@ -2367,8 +2367,8 @@ 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);