From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id rhswIP5IGVuGTAAAmS7hNA ; Thu, 07 Jun 2018 15:04:03 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id BB55B608BF; Thu, 7 Jun 2018 15:04:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 1F2DF601C3; Thu, 7 Jun 2018 15:04:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 1F2DF601C3 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936014AbeFGPD7 (ORCPT + 25 others); Thu, 7 Jun 2018 11:03:59 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41545 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935962AbeFGPDx (ORCPT ); Thu, 7 Jun 2018 11:03:53 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvbj-0005Zj-97; Thu, 07 Jun 2018 15:09:43 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvb5-0002ya-BS; Thu, 07 Jun 2018 15:09:03 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Josef Bacik" , "Liu Bo" , "David Sterba" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 189/410] Btrfs: fix use-after-free on root->orphan_block_rsv In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Liu Bo commit 1a932ef4e47984dee227834667b5ff5a334e4805 upstream. I got these from running generic/475, WARNING: CPU: 0 PID: 26384 at fs/btrfs/inode.c:3326 btrfs_orphan_commit_root+0x1ac/0x2b0 [btrfs] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 IP: btrfs_block_rsv_release+0x1c/0x70 [btrfs] Call Trace: btrfs_orphan_release_metadata+0x9f/0x200 [btrfs] btrfs_orphan_del+0x10d/0x170 [btrfs] btrfs_setattr+0x500/0x640 [btrfs] notify_change+0x7ae/0x870 do_truncate+0xca/0x130 vfs_truncate+0x2ee/0x3d0 do_sys_truncate+0xaf/0xf0 SyS_truncate+0xe/0x10 entry_SYSCALL_64_fastpath+0x1f/0x96 The race is between btrfs_orphan_commit_root and btrfs_orphan_del, t1 t2 btrfs_orphan_commit_root btrfs_orphan_del spin_lock check (&root->orphan_inodes) root->orphan_block_rsv = NULL; spin_unlock atomic_dec(&root->orphan_inodes); access root->orphan_block_rsv Accessing root->orphan_block_rsv must be done before decreasing root->orphan_inodes. Fixes: 703c88e03524 ("Btrfs: fix tracking of orphan inode count") Signed-off-by: Liu Bo Reviewed-by: Josef Bacik Signed-off-by: David Sterba [bwh: Backported to 3.16: Drop the added comment in a path that's unreachable here] Signed-off-by: Ben Hutchings --- fs/btrfs/inode.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3082,12 +3082,17 @@ int btrfs_orphan_add(struct btrfs_trans_ if (insert >= 1) { ret = btrfs_insert_orphan_item(trans, root, btrfs_ino(inode)); if (ret) { - atomic_dec(&root->orphan_inodes); if (reserve) { clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED, &BTRFS_I(inode)->runtime_flags); btrfs_orphan_release_metadata(inode); } + /* + * btrfs_orphan_commit_root may race with us and set + * ->orphan_block_rsv to zero, in order to avoid that, + * decrease ->orphan_inodes after everything is done. + */ + atomic_dec(&root->orphan_inodes); if (ret != -EEXIST) { clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM, &BTRFS_I(inode)->runtime_flags); @@ -3119,28 +3124,26 @@ static int btrfs_orphan_del(struct btrfs { struct btrfs_root *root = BTRFS_I(inode)->root; int delete_item = 0; - int release_rsv = 0; int ret = 0; - spin_lock(&root->orphan_lock); if (test_and_clear_bit(BTRFS_INODE_HAS_ORPHAN_ITEM, &BTRFS_I(inode)->runtime_flags)) delete_item = 1; + if (delete_item && trans) + ret = btrfs_del_orphan_item(trans, root, btrfs_ino(inode)); + if (test_and_clear_bit(BTRFS_INODE_ORPHAN_META_RESERVED, &BTRFS_I(inode)->runtime_flags)) - release_rsv = 1; - spin_unlock(&root->orphan_lock); + btrfs_orphan_release_metadata(inode); - if (delete_item) { + /* + * btrfs_orphan_commit_root may race with us and set ->orphan_block_rsv + * to zero, in order to avoid that, decrease ->orphan_inodes after + * everything is done. + */ + if (delete_item) atomic_dec(&root->orphan_inodes); - if (trans) - ret = btrfs_del_orphan_item(trans, root, - btrfs_ino(inode)); - } - - if (release_rsv) - btrfs_orphan_release_metadata(inode); return ret; }