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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 89866C282CE for ; Wed, 22 May 2019 20:00:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A50E21019 for ; Wed, 22 May 2019 20:00:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558555245; bh=Nv5cGBCFnMfTv8Ai6NBu5Z5YCU0ScEgWsk8kly9DXlg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Brl5Ybf3iLFj0HkoVOz7prz6UuJjlo9J5ea+4RLbW+iwpzjXQ8skbp0NrQ+sHUgBe N3iUA++LOw0MzwtRUQyqrVrtV3Y2sdmWkHzN9+Y49cj1A3H2DVLXiaGygyM6K5hVaW xe4JNVekvN5nPR1yY0tnPF+hnbliuz+Kd1wlpa9Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730681AbfEVTXA (ORCPT ); Wed, 22 May 2019 15:23:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:43804 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730677AbfEVTW7 (ORCPT ); Wed, 22 May 2019 15:22:59 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 76737217D7; Wed, 22 May 2019 19:22:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558552978; bh=Nv5cGBCFnMfTv8Ai6NBu5Z5YCU0ScEgWsk8kly9DXlg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gEE10QKCic2vRrv9o00LjQzar9xLOJF40v5/ifLMpEPF72u1Kzu2iZmM2HILeHYlE qQH5SncL/pIAeplBWdaZwnrgjfELSJ87G5wFBsvuLgzBEkUU/N5Lb5n9ZZq7qj1TsP rCsmqJKQ3CQQB7ObWn+JunkaPDxJrhKGkFknnyH8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Qu Wenruo , David Sterba , Sasha Levin , linux-btrfs@vger.kernel.org Subject: [PATCH AUTOSEL 5.1 058/375] btrfs: reloc: Fix NULL pointer dereference due to expanded reloc_root lifespan Date: Wed, 22 May 2019 15:15:58 -0400 Message-Id: <20190522192115.22666-58-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522192115.22666-1-sashal@kernel.org> References: <20190522192115.22666-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Qu Wenruo [ Upstream commit 10995c0491204c861948c9850939a7f4e90760a4 ] Commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots()") expands the life span of root->reloc_root. This breaks certain checs of fs_info->reloc_ctl. Before that commit, if we have a root with valid reloc_root, then it's ensured to have fs_info->reloc_ctl. But now since reloc_root doesn't always mean a valid fs_info->reloc_ctl, such check is unreliable and can cause the following NULL pointer dereference: BUG: unable to handle kernel NULL pointer dereference at 00000000000005c1 IP: btrfs_reloc_pre_snapshot+0x20/0x50 [btrfs] PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 10379 Comm: snapperd Not tainted Call Trace: create_pending_snapshot+0xd7/0xfc0 [btrfs] create_pending_snapshots+0x8e/0xb0 [btrfs] btrfs_commit_transaction+0x2ac/0x8f0 [btrfs] btrfs_mksubvol+0x561/0x570 [btrfs] btrfs_ioctl_snap_create_transid+0x189/0x190 [btrfs] btrfs_ioctl_snap_create_v2+0x102/0x150 [btrfs] btrfs_ioctl+0x5c9/0x1e60 [btrfs] do_vfs_ioctl+0x90/0x5f0 SyS_ioctl+0x74/0x80 do_syscall_64+0x7b/0x150 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x7fd7cdab8467 Fix it by explicitly checking fs_info->reloc_ctl other than using the implied root->reloc_root. Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/relocation.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 00c3dd92f088f..1d82ee4883eb3 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4676,14 +4676,12 @@ int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans, void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending, u64 *bytes_to_reserve) { - struct btrfs_root *root; - struct reloc_control *rc; + struct btrfs_root *root = pending->root; + struct reloc_control *rc = root->fs_info->reloc_ctl; - root = pending->root; - if (!root->reloc_root) + if (!root->reloc_root || !rc) return; - rc = root->fs_info->reloc_ctl; if (!rc->merge_reloc_tree) return; @@ -4712,10 +4710,10 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root *root = pending->root; struct btrfs_root *reloc_root; struct btrfs_root *new_root; - struct reloc_control *rc; + struct reloc_control *rc = root->fs_info->reloc_ctl; int ret; - if (!root->reloc_root) + if (!root->reloc_root || !rc) return 0; rc = root->fs_info->reloc_ctl; -- 2.20.1