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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,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 39A2BC282DD for ; Thu, 23 May 2019 19:31:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1051B20879 for ; Thu, 23 May 2019 19:31:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558639907; bh=Jfx6KeEU+O9GHSS13gWnKqZraw3gOIgsyaXRRt0RtWM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pNd3zDzH9xuNIaNlqmxhDXcnZ/lf40kiR9PbGLovgR3OegHByGPv11K+CiZDSsuwA I9y0lOUJYehsMhDP5BWZNKZSrtXM71cJG9cwYy1ASG4ZZRZT2fOZGPfawNrCpJSTdq X2a1VFO8FvFlnQyhmVXiMa9zNv8P9EMl6XTj3YP4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392023AbfEWTb0 (ORCPT ); Thu, 23 May 2019 15:31:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:45246 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392017AbfEWTb0 (ORCPT ); Thu, 23 May 2019 15:31:26 -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 C9C5E2054F; Thu, 23 May 2019 19:31:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558639885; bh=Jfx6KeEU+O9GHSS13gWnKqZraw3gOIgsyaXRRt0RtWM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S1GhhxowjzyHBUGmDvU1/l70m+Pa/MSaIFQI+KwBEIDG4a0Uy4O01qj36AdZgItHW UWq1Y5NY7Ws5k08kseqJukBzwvZ8SsjN8v1pdb7hDJKLvFhmZuIY9BulOg/qamysIj Gt7Hze7njXTAqtr9eYPDq3xadqkzmdWcNlY28ao8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qu Wenruo , David Sterba Subject: [PATCH 5.1 120/122] btrfs: reloc: Fix NULL pointer dereference due to expanded reloc_root lifespan Date: Thu, 23 May 2019 21:07:22 +0200 Message-Id: <20190523181721.457475819@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523181705.091418060@linuxfoundation.org> References: <20190523181705.091418060@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: Qu Wenruo commit 10995c0491204c861948c9850939a7f4e90760a4 upstream. 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: Greg Kroah-Hartman --- fs/btrfs/relocation.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4667,14 +4667,12 @@ int btrfs_reloc_cow_block(struct btrfs_t 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; @@ -4703,10 +4701,10 @@ int btrfs_reloc_post_snapshot(struct btr 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;