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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 8395DC2BD09 for ; Wed, 11 Dec 2019 05:00:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 647E720836 for ; Wed, 11 Dec 2019 05:00:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726494AbfLKFAP (ORCPT ); Wed, 11 Dec 2019 00:00:15 -0500 Received: from mx2.suse.de ([195.135.220.15]:45524 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725768AbfLKFAP (ORCPT ); Wed, 11 Dec 2019 00:00:15 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 61AD6AE34; Wed, 11 Dec 2019 05:00:13 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: Zygo Blaxell Subject: [PATCH 2/3] btrfs: relocation: Fix KASAN report on create_reloc_tree due to extended reloc tree lifepsan Date: Wed, 11 Dec 2019 13:00:03 +0800 Message-Id: <20191211050004.18414-3-wqu@suse.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191211050004.18414-1-wqu@suse.com> References: <20191211050004.18414-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org [BUG] When running workload with balance start/cancel, snapshot creation/deletion and fsstress, we can hit the following KASAN report: ================================================================== BUG: KASAN: use-after-free in create_reloc_root+0x9f/0x460 [btrfs] Read of size 8 at addr ffff8881571741f0 by task btrfs/3539 CPU: 6 PID: 3539 Comm: btrfs Tainted: G O 5.5.0-rc1-custom+ #40 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack+0xc2/0x11a print_address_description.constprop.0+0x20/0x210 __kasan_report.cold+0x1b/0x41 kasan_report+0x12/0x20 __asan_load8+0x54/0x90 create_reloc_root+0x9f/0x460 [btrfs] btrfs_reloc_post_snapshot+0xff/0x6c0 [btrfs] create_pending_snapshot+0xa9b/0x15f0 [btrfs] create_pending_snapshots+0x111/0x140 [btrfs] btrfs_commit_transaction+0x7a6/0x1360 [btrfs] btrfs_mksubvol+0x915/0x960 [btrfs] btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs] btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs] btrfs_ioctl+0x241b/0x3e60 [btrfs] do_vfs_ioctl+0x831/0xb10 ksys_ioctl+0x67/0x90 __x64_sys_ioctl+0x43/0x50 do_syscall_64+0x79/0xe0 entry_SYSCALL_64_after_hwframe+0x49/0xbe [CAUSE] This is another case where root->reloc_root is accessed without checking if the reloc root is already dead. [FIX] Also check DEAD_RELOC_TREE bit before accessing root->reloc_root. Reported-by: Zygo Blaxell Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") Signed-off-by: Qu Wenruo --- fs/btrfs/relocation.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index bb41b981e493..619ccb183515 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4755,7 +4755,14 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, struct reloc_control *rc = root->fs_info->reloc_ctl; int ret; - if (!root->reloc_root || !rc) + /* + * We don't need to use reloc tree if: + * - No reloc tree + * - Relocation not running + * - Reloc tree already merged + */ + if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, + &root->state)) return 0; rc = root->fs_info->reloc_ctl; -- 2.24.0