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=-6.0 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 C22C7C04AAC for ; Mon, 20 May 2019 12:37:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96643204FD for ; Mon, 20 May 2019 12:37:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558355876; bh=Y+8Y21qUCRMYjTUDfur/iQJvKkhuVBO32bLyVOUL494=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eL5FJzub3/nuja4n74NPdzSkmfDDPhVfwaighW4ebyr0lCWFlaIQQLl+97zkyHpaY f44tUZEtMEnX//nnMmH7UIfC2KMmRxFFp+9varn3QRVMjqMhW5umPnOYRclxoiqTfV jdsXc0cKxwI/a8r1vNgo0OUFp+A6wPkFxu7zB+28= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403851AbfETMfo (ORCPT ); Mon, 20 May 2019 08:35:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:54432 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390795AbfETMfo (ORCPT ); Mon, 20 May 2019 08:35:44 -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 3295C216C4; Mon, 20 May 2019 12:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558355743; bh=Y+8Y21qUCRMYjTUDfur/iQJvKkhuVBO32bLyVOUL494=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=igDgB5haT3zhFgPc/8ITaa82Ki9BisyfvxRdb76S++6FUC7zvPP19174mErbZrbcN 61+otQBqDTwM7LoLQvTH7KlMv+BoMCUmOH4pukKlNkv7PGcblkZn+joX9oUc/or+qC UMQVG3xOe/S/degnSYn5KN2lAyYR7va5pHp5nLLk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sahitya Tummala , Theodore Tso , Andreas Dilger , stable@kernel.org Subject: [PATCH 5.1 109/128] ext4: fix use-after-free in dx_release() Date: Mon, 20 May 2019 14:14:56 +0200 Message-Id: <20190520115256.358805739@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190520115249.449077487@linuxfoundation.org> References: <20190520115249.449077487@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sahitya Tummala commit 08fc98a4d6424af66eb3ac4e2cedd2fc927ed436 upstream. The buffer_head (frames[0].bh) and it's corresping page can be potentially free'd once brelse() is done inside the for loop but before the for loop exits in dx_release(). It can be free'd in another context, when the page cache is flushed via drop_caches_sysctl_handler(). This results into below data abort when accessing info->indirect_levels in dx_release(). Unable to handle kernel paging request at virtual address ffffffc17ac3e01e Call trace: dx_release+0x70/0x90 ext4_htree_fill_tree+0x2d4/0x300 ext4_readdir+0x244/0x6f8 iterate_dir+0xbc/0x160 SyS_getdents64+0x94/0x174 Signed-off-by: Sahitya Tummala Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/ext4/namei.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -871,12 +871,15 @@ static void dx_release(struct dx_frame * { struct dx_root_info *info; int i; + unsigned int indirect_levels; if (frames[0].bh == NULL) return; info = &((struct dx_root *)frames[0].bh->b_data)->info; - for (i = 0; i <= info->indirect_levels; i++) { + /* save local copy, "info" may be freed after brelse() */ + indirect_levels = info->indirect_levels; + for (i = 0; i <= indirect_levels; i++) { if (frames[i].bh == NULL) break; brelse(frames[i].bh);