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=-6.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 78C2AC43441 for ; Sun, 11 Nov 2018 23:25:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 41B8B2084C for ; Sun, 11 Nov 2018 23:25:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZWbO29gt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41B8B2084C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389093AbeKLIUs (ORCPT ); Mon, 12 Nov 2018 03:20:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:46600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733238AbeKLIUs (ORCPT ); Mon, 12 Nov 2018 03:20:48 -0500 Received: from localhost (unknown [206.108.79.134]) (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 62CF1223CA; Sun, 11 Nov 2018 22:30:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541975451; bh=4Ntq5c92oVm1/yETUZWrtff/mqoymfcTVwWlBMJXdzk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZWbO29gt0vfedz7Fv+dPSSzzbble35kFAed6MrsL0e/t+k87w5S0FgBqUTbVmlx4G IjWfrcDSREW6rbtrmgXKrL35NuSvQV/vvt5lKTBBgHINciaY3xqJqVnHs/CQ+OMwGv qMXwrn42pxKhIvpzPI77IA0li3A6N5gpP3b3Wukw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+7f4a27091759e2fe7453@syzkaller.appspotmail.com, Lukas Czerner , Jan Kara , Theodore Tso Subject: [PATCH 4.18 218/350] jbd2: fix use after free in jbd2_log_do_checkpoint() Date: Sun, 11 Nov 2018 14:21:22 -0800 Message-Id: <20181111221717.146841015@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181111221707.043394111@linuxfoundation.org> References: <20181111221707.043394111@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review 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 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit ccd3c4373eacb044eb3832966299d13d2631f66f upstream. The code cleaning transaction's lists of checkpoint buffers has a bug where it increases bh refcount only after releasing journal->j_list_lock. Thus the following race is possible: CPU0 CPU1 jbd2_log_do_checkpoint() jbd2_journal_try_to_free_buffers() __journal_try_to_free_buffer(bh) ... while (transaction->t_checkpoint_io_list) ... if (buffer_locked(bh)) { <-- IO completes now, buffer gets unlocked --> spin_unlock(&journal->j_list_lock); spin_lock(&journal->j_list_lock); __jbd2_journal_remove_checkpoint(jh); spin_unlock(&journal->j_list_lock); try_to_free_buffers(page); get_bh(bh) <-- accesses freed bh Fix the problem by grabbing bh reference before unlocking journal->j_list_lock. Fixes: dc6e8d669cf5 ("jbd2: don't call get_bh() before calling __jbd2_journal_remove_checkpoint()") Fixes: be1158cc615f ("jbd2: fold __process_buffer() into jbd2_log_do_checkpoint()") Reported-by: syzbot+7f4a27091759e2fe7453@syzkaller.appspotmail.com CC: stable@vger.kernel.org Reviewed-by: Lukas Czerner Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/jbd2/checkpoint.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -251,8 +251,8 @@ restart: bh = jh2bh(jh); if (buffer_locked(bh)) { - spin_unlock(&journal->j_list_lock); get_bh(bh); + spin_unlock(&journal->j_list_lock); wait_on_buffer(bh); /* the journal_head may have gone by now */ BUFFER_TRACE(bh, "brelse"); @@ -333,8 +333,8 @@ restart2: jh = transaction->t_checkpoint_io_list; bh = jh2bh(jh); if (buffer_locked(bh)) { - spin_unlock(&journal->j_list_lock); get_bh(bh); + spin_unlock(&journal->j_list_lock); wait_on_buffer(bh); /* the journal_head may have gone by now */ BUFFER_TRACE(bh, "brelse");