From patchwork Mon Oct 22 09:43:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 10651889 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DA32513A4 for ; Mon, 22 Oct 2018 09:43:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CDB192874F for ; Mon, 22 Oct 2018 09:43:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C1955288B5; Mon, 22 Oct 2018 09:43:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D3DD82874F for ; Mon, 22 Oct 2018 09:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728451AbeJVSA5 (ORCPT ); Mon, 22 Oct 2018 14:00:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:36162 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728348AbeJVSA5 (ORCPT ); Mon, 22 Oct 2018 14:00:57 -0400 Received: from localhost.localdomain (bl8-197-74.dsl.telepac.pt [85.241.197.74]) (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 8F44320652 for ; Mon, 22 Oct 2018 09:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540201390; bh=TY6dEVjjjcSYxb+UefK3/eeLU1b77+x2akgQYy6sWqM=; h=From:To:Subject:Date:From; b=d10Mu0dikxFvSAHBpGeXQgLCOWwvyGzKg00ZfeTbiwNAbxceSW3gNn0EbaWAxh9F5 yvlINY8DWqbKdDKszEYukxdmnuZurH+ySTIjvedTL3tlSCqBMHnWcRyZeNueC7On5p VjxsH+xMcY992EAHcaIXP4it1t8Vsbr3pNLezudU= From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH] Btrfs: fix use-after-free when dumping free space Date: Mon, 22 Oct 2018 10:43:06 +0100 Message-Id: <20181022094306.28868-1-fdmanana@kernel.org> X-Mailer: git-send-email 2.11.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Filipe Manana We were iterating a block group's free space cache rbtree without locking first the lock that protects it (the free_space_ctl->free_space_offset rbtree is protected by the free_space_ctl->tree_lock spinlock). KASAN reported an use-after-free problem when iterating such a rbtree due to a concurrent rbtree delete: [ 9520.359168] ================================================================== [ 9520.359656] BUG: KASAN: use-after-free in rb_next+0x13/0x90 [ 9520.359949] Read of size 8 at addr ffff8800b7ada500 by task btrfs-transacti/1721 [ 9520.360357] [ 9520.360530] CPU: 4 PID: 1721 Comm: btrfs-transacti Tainted: G L 4.19.0-rc8-nbor #555 [ 9520.360990] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 9520.362682] Call Trace: [ 9520.362887] dump_stack+0xa4/0xf5 [ 9520.363146] print_address_description+0x78/0x280 [ 9520.363412] kasan_report+0x263/0x390 [ 9520.363650] ? rb_next+0x13/0x90 [ 9520.363873] __asan_load8+0x54/0x90 [ 9520.364102] rb_next+0x13/0x90 [ 9520.364380] btrfs_dump_free_space+0x146/0x160 [btrfs] [ 9520.364697] dump_space_info+0x2cd/0x310 [btrfs] [ 9520.364997] btrfs_reserve_extent+0x1ee/0x1f0 [btrfs] [ 9520.365310] __btrfs_prealloc_file_range+0x1cc/0x620 [btrfs] [ 9520.365646] ? btrfs_update_time+0x180/0x180 [btrfs] [ 9520.365923] ? _raw_spin_unlock+0x27/0x40 [ 9520.366204] ? btrfs_alloc_data_chunk_ondemand+0x2c0/0x5c0 [btrfs] [ 9520.366549] btrfs_prealloc_file_range_trans+0x23/0x30 [btrfs] [ 9520.366880] cache_save_setup+0x42e/0x580 [btrfs] [ 9520.367220] ? btrfs_check_data_free_space+0xd0/0xd0 [btrfs] [ 9520.367518] ? lock_downgrade+0x2f0/0x2f0 [ 9520.367799] ? btrfs_write_dirty_block_groups+0x11f/0x6e0 [btrfs] [ 9520.368104] ? kasan_check_read+0x11/0x20 [ 9520.368349] ? do_raw_spin_unlock+0xa8/0x140 [ 9520.368638] btrfs_write_dirty_block_groups+0x2af/0x6e0 [btrfs] [ 9520.368978] ? btrfs_start_dirty_block_groups+0x870/0x870 [btrfs] [ 9520.369282] ? do_raw_spin_unlock+0xa8/0x140 [ 9520.369534] ? _raw_spin_unlock+0x27/0x40 [ 9520.369811] ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs] [ 9520.370137] commit_cowonly_roots+0x4b9/0x610 [btrfs] [ 9520.370560] ? commit_fs_roots+0x350/0x350 [btrfs] [ 9520.370926] ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs] [ 9520.371285] btrfs_commit_transaction+0x5e5/0x10e0 [btrfs] [ 9520.371612] ? btrfs_apply_pending_changes+0x90/0x90 [btrfs] [ 9520.371943] ? start_transaction+0x168/0x6c0 [btrfs] [ 9520.372257] transaction_kthread+0x21c/0x240 [btrfs] [ 9520.372537] kthread+0x1d2/0x1f0 [ 9520.372793] ? btrfs_cleanup_transaction+0xb50/0xb50 [btrfs] [ 9520.373090] ? kthread_park+0xb0/0xb0 [ 9520.373329] ret_from_fork+0x3a/0x50 [ 9520.373567] [ 9520.373738] Allocated by task 1804: [ 9520.373974] kasan_kmalloc+0xff/0x180 [ 9520.374208] kasan_slab_alloc+0x11/0x20 [ 9520.374447] kmem_cache_alloc+0xfc/0x2d0 [ 9520.374731] __btrfs_add_free_space+0x40/0x580 [btrfs] [ 9520.375044] unpin_extent_range+0x4f7/0x7a0 [btrfs] [ 9520.375383] btrfs_finish_extent_commit+0x15f/0x4d0 [btrfs] [ 9520.375707] btrfs_commit_transaction+0xb06/0x10e0 [btrfs] [ 9520.376027] btrfs_alloc_data_chunk_ondemand+0x237/0x5c0 [btrfs] [ 9520.376365] btrfs_check_data_free_space+0x81/0xd0 [btrfs] [ 9520.376689] btrfs_delalloc_reserve_space+0x25/0x80 [btrfs] [ 9520.377018] btrfs_direct_IO+0x42e/0x6d0 [btrfs] [ 9520.377284] generic_file_direct_write+0x11e/0x220 [ 9520.377587] btrfs_file_write_iter+0x472/0xac0 [btrfs] [ 9520.377875] aio_write+0x25c/0x360 [ 9520.378106] io_submit_one+0xaa0/0xdc0 [ 9520.378343] __se_sys_io_submit+0xfa/0x2f0 [ 9520.378589] __x64_sys_io_submit+0x43/0x50 [ 9520.378840] do_syscall_64+0x7d/0x240 [ 9520.379081] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 9520.379387] [ 9520.379557] Freed by task 1802: [ 9520.379782] __kasan_slab_free+0x173/0x260 [ 9520.380028] kasan_slab_free+0xe/0x10 [ 9520.380262] kmem_cache_free+0xc1/0x2c0 [ 9520.380544] btrfs_find_space_for_alloc+0x4cd/0x4e0 [btrfs] [ 9520.380866] find_free_extent+0xa99/0x17e0 [btrfs] [ 9520.381166] btrfs_reserve_extent+0xd5/0x1f0 [btrfs] [ 9520.381474] btrfs_get_blocks_direct+0x60b/0xbd0 [btrfs] [ 9520.381761] __blockdev_direct_IO+0x10ee/0x58a1 [ 9520.382059] btrfs_direct_IO+0x25a/0x6d0 [btrfs] [ 9520.382321] generic_file_direct_write+0x11e/0x220 [ 9520.382623] btrfs_file_write_iter+0x472/0xac0 [btrfs] [ 9520.382904] aio_write+0x25c/0x360 [ 9520.383172] io_submit_one+0xaa0/0xdc0 [ 9520.383416] __se_sys_io_submit+0xfa/0x2f0 [ 9520.383678] __x64_sys_io_submit+0x43/0x50 [ 9520.383927] do_syscall_64+0x7d/0x240 [ 9520.384165] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 9520.384439] [ 9520.384610] The buggy address belongs to the object at ffff8800b7ada500 which belongs to the cache btrfs_free_space of size 72 [ 9520.385175] The buggy address is located 0 bytes inside of 72-byte region [ffff8800b7ada500, ffff8800b7ada548) [ 9520.385691] The buggy address belongs to the page: [ 9520.385957] page:ffffea0002deb680 count:1 mapcount:0 mapping:ffff880108a1d700 index:0x0 compound_mapcount: 0 [ 9520.388030] flags: 0x8100(slab|head) [ 9520.388281] raw: 0000000000008100 ffffea0002deb608 ffffea0002728808 ffff880108a1d700 [ 9520.388722] raw: 0000000000000000 0000000000130013 00000001ffffffff 0000000000000000 [ 9520.389169] page dumped because: kasan: bad access detected [ 9520.389473] [ 9520.389658] Memory state around the buggy address: [ 9520.389943] ffff8800b7ada400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 9520.390368] ffff8800b7ada480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 9520.390796] >ffff8800b7ada500: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 9520.391223] ^ [ 9520.391461] ffff8800b7ada580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 9520.391885] ffff8800b7ada600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 9520.392313] ================================================================== [ 9520.392772] BTRFS critical (device vdc): entry offset 2258497536, bytes 131072, bitmap no [ 9520.393247] BUG: unable to handle kernel NULL pointer dereference at 0000000000000011 [ 9520.393705] PGD 800000010dbab067 P4D 800000010dbab067 PUD 107551067 PMD 0 [ 9520.394059] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 9520.394378] CPU: 4 PID: 1721 Comm: btrfs-transacti Tainted: G B L 4.19.0-rc8-nbor #555 [ 9520.394858] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 9520.395350] RIP: 0010:rb_next+0x3c/0x90 [ 9520.396461] RSP: 0018:ffff8801074ff780 EFLAGS: 00010292 [ 9520.396762] RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81b5ac4c [ 9520.397115] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000011 [ 9520.397468] RBP: ffff8801074ff7a0 R08: ffffed0021d64ccc R09: ffffed0021d64ccc [ 9520.397821] R10: 0000000000000001 R11: ffffed0021d64ccb R12: ffff8800b91e0000 [ 9520.398188] R13: ffff8800a3ceba48 R14: ffff8800b627bf80 R15: 0000000000020000 [ 9520.398555] FS: 0000000000000000(0000) GS:ffff88010eb00000(0000) knlGS:0000000000000000 [ 9520.399007] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9520.399335] CR2: 0000000000000011 CR3: 0000000106b52000 CR4: 00000000000006a0 [ 9520.399679] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 9520.400023] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 9520.400400] Call Trace: [ 9520.400648] btrfs_dump_free_space+0x146/0x160 [btrfs] [ 9520.400974] dump_space_info+0x2cd/0x310 [btrfs] [ 9520.401287] btrfs_reserve_extent+0x1ee/0x1f0 [btrfs] [ 9520.401609] __btrfs_prealloc_file_range+0x1cc/0x620 [btrfs] [ 9520.401952] ? btrfs_update_time+0x180/0x180 [btrfs] [ 9520.402232] ? _raw_spin_unlock+0x27/0x40 [ 9520.402522] ? btrfs_alloc_data_chunk_ondemand+0x2c0/0x5c0 [btrfs] [ 9520.402882] btrfs_prealloc_file_range_trans+0x23/0x30 [btrfs] [ 9520.403261] cache_save_setup+0x42e/0x580 [btrfs] [ 9520.403570] ? btrfs_check_data_free_space+0xd0/0xd0 [btrfs] [ 9520.403871] ? lock_downgrade+0x2f0/0x2f0 [ 9520.404161] ? btrfs_write_dirty_block_groups+0x11f/0x6e0 [btrfs] [ 9520.404481] ? kasan_check_read+0x11/0x20 [ 9520.404732] ? do_raw_spin_unlock+0xa8/0x140 [ 9520.405026] btrfs_write_dirty_block_groups+0x2af/0x6e0 [btrfs] [ 9520.405375] ? btrfs_start_dirty_block_groups+0x870/0x870 [btrfs] [ 9520.405694] ? do_raw_spin_unlock+0xa8/0x140 [ 9520.405958] ? _raw_spin_unlock+0x27/0x40 [ 9520.406243] ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs] [ 9520.406574] commit_cowonly_roots+0x4b9/0x610 [btrfs] [ 9520.406899] ? commit_fs_roots+0x350/0x350 [btrfs] [ 9520.407253] ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs] [ 9520.407589] btrfs_commit_transaction+0x5e5/0x10e0 [btrfs] [ 9520.407925] ? btrfs_apply_pending_changes+0x90/0x90 [btrfs] [ 9520.408262] ? start_transaction+0x168/0x6c0 [btrfs] [ 9520.408582] transaction_kthread+0x21c/0x240 [btrfs] [ 9520.408870] kthread+0x1d2/0x1f0 [ 9520.409138] ? btrfs_cleanup_transaction+0xb50/0xb50 [btrfs] [ 9520.409440] ? kthread_park+0xb0/0xb0 [ 9520.409682] ret_from_fork+0x3a/0x50 [ 9520.410508] Dumping ftrace buffer: [ 9520.410764] (ftrace buffer empty) [ 9520.411007] CR2: 0000000000000011 [ 9520.411297] ---[ end trace 01a0863445cf360a ]--- [ 9520.411568] RIP: 0010:rb_next+0x3c/0x90 [ 9520.412644] RSP: 0018:ffff8801074ff780 EFLAGS: 00010292 [ 9520.412932] RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81b5ac4c [ 9520.413274] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000011 [ 9520.413616] RBP: ffff8801074ff7a0 R08: ffffed0021d64ccc R09: ffffed0021d64ccc [ 9520.414007] R10: 0000000000000001 R11: ffffed0021d64ccb R12: ffff8800b91e0000 [ 9520.414349] R13: ffff8800a3ceba48 R14: ffff8800b627bf80 R15: 0000000000020000 [ 9520.416074] FS: 0000000000000000(0000) GS:ffff88010eb00000(0000) knlGS:0000000000000000 [ 9520.416536] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9520.416848] CR2: 0000000000000011 CR3: 0000000106b52000 CR4: 00000000000006a0 [ 9520.418477] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 9520.418846] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 9520.419204] Kernel panic - not syncing: Fatal exception [ 9520.419666] Dumping ftrace buffer: [ 9520.419930] (ftrace buffer empty) [ 9520.420168] Kernel Offset: disabled [ 9520.420406] ---[ end Kernel panic - not syncing: Fatal exception ]--- Fix this by acquiring the respective lock before iterating the rbtree. Reported-by: Nikolay Borisov Signed-off-by: Filipe Manana Reviewed-by: Josef Bacik --- fs/btrfs/free-space-cache.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 0adf38b00fa0..65b79500e09f 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2440,6 +2440,7 @@ void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group, struct rb_node *n; int count = 0; + spin_lock(&ctl->tree_lock); for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) { info = rb_entry(n, struct btrfs_free_space, offset_index); if (info->bytes >= bytes && !block_group->ro) @@ -2448,6 +2449,7 @@ void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group, info->offset, info->bytes, (info->bitmap) ? "yes" : "no"); } + spin_unlock(&ctl->tree_lock); btrfs_info(fs_info, "block group has cluster?: %s", list_empty(&block_group->cluster_list) ? "no" : "yes"); btrfs_info(fs_info,