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Thu, 25 Jul 2019 05:26:39 -0400 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 E465EADBF for ; Thu, 25 Jul 2019 09:26:36 +0000 (UTC) Subject: Re: [PATCH v2 3/5] btrfs: Detect unbalanced tree with empty leaf before crashing btree operations To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <20190725061222.9581-1-wqu@suse.com> <20190725061222.9581-4-wqu@suse.com> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: <6dbec951-751d-cd48-d20c-bc558cf213e0@suse.com> Date: Thu, 25 Jul 2019 12:26:35 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190725061222.9581-4-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 25.07.19 г. 9:12 ч., Qu Wenruo wrote: > [BUG] > With crafted image, btrfs will panic at btree operations: > kernel BUG at fs/btrfs/ctree.c:3894! > invalid opcode: 0000 [#1] SMP PTI > CPU: 0 PID: 1138 Comm: btrfs-transacti Not tainted 5.0.0-rc8+ #9 > RIP: 0010:__push_leaf_left+0x6b6/0x6e0 > Code: 00 00 48 98 48 8d 04 80 48 8d 74 80 65 e8 42 5a 04 00 48 8b bd 78 ff ff ff 8b bf 90 d0 00 00 89 7d 98 83 ef 65 e9 06 ff ff ff <0f> 0b 0f 0b 48 8b 85 78 ff ff ff 8b 90 90 d0 00 00 e9 eb fe ff ff > RSP: 0018:ffffc0bd4128b990 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffffa0a4ab8f0e38 RCX: 0000000000000000 > RDX: ffffa0a280000000 RSI: 0000000000000000 RDI: ffffa0a4b3814000 > RBP: ffffc0bd4128ba38 R08: 0000000000001000 R09: ffffc0bd4128b948 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000240 > R13: ffffa0a4b556fb60 R14: ffffa0a4ab8f0af0 R15: ffffa0a4ab8f0af0 > FS: 0000000000000000(0000) GS:ffffa0a4b7a00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f2461c80020 CR3: 000000022b32a006 CR4: 00000000000206f0 > Call Trace: > ? _cond_resched+0x1a/0x50 > push_leaf_left+0x179/0x190 > btrfs_del_items+0x316/0x470 > btrfs_del_csums+0x215/0x3a0 > __btrfs_free_extent.isra.72+0x5a7/0xbe0 > __btrfs_run_delayed_refs+0x539/0x1120 > btrfs_run_delayed_refs+0xdb/0x1b0 > btrfs_commit_transaction+0x52/0x950 > ? start_transaction+0x94/0x450 > transaction_kthread+0x163/0x190 > kthread+0x105/0x140 > ? btrfs_cleanup_transaction+0x560/0x560 > ? kthread_destroy_worker+0x50/0x50 > ret_from_fork+0x35/0x40 > Modules linked in: > ---[ end trace c2425e6e89b5558f ]--- > > [CAUSE] > The offending csum tree looks like this: > checksum tree key (CSUM_TREE ROOT_ITEM 0) > node 29741056 level 1 items 14 free 107 generation 19 owner CSUM_TREE > ... > key (EXTENT_CSUM EXTENT_CSUM 85975040) block 29630464 gen 17 > key (EXTENT_CSUM EXTENT_CSUM 89911296) block 29642752 gen 17 <<< > key (EXTENT_CSUM EXTENT_CSUM 92274688) block 29646848 gen 17 > ... > > leaf 29630464 items 6 free space 1 generation 17 owner CSUM_TREE > item 0 key (EXTENT_CSUM EXTENT_CSUM 85975040) itemoff 3987 itemsize 8 > range start 85975040 end 85983232 length 8192 > ... > leaf 29642752 items 0 free space 3995 generation 17 owner 0 > ^ empty leaf invalid owner ^ > > leaf 29646848 items 1 free space 602 generation 17 owner CSUM_TREE > item 0 key (EXTENT_CSUM EXTENT_CSUM 92274688) itemoff 627 itemsize 3368 > range start 92274688 end 95723520 length 3448832 > > So we have a corrupted csum tree where one tree leaf is completely > empty, causing unbalanced btree, thus leading to unexpected btree > balance error. > > [FIX] > For this particular case, we handle it in two directions to catch it: > - Check if the tree block is empty through btrfs_verify_level_key() > So that invalid tree blocks won't be read out through > btrfs_search_slot() and its variants. > > - Check 0 tree owner in tree checker > NO tree is using 0 as its tree owner, detect it and reject at tree > block read time. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=202821 > Signed-off-by: Qu Wenruo > --- > fs/btrfs/disk-io.c | 8 ++++++++ > fs/btrfs/tree-checker.c | 6 ++++++ > 2 files changed, 14 insertions(+) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index deb74a8c191a..a843c21f3060 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -414,6 +414,14 @@ int btrfs_verify_level_key(struct extent_buffer *eb, int level, > > if (!first_key) > return 0; > + /* We have @first_key, so this @eb must have at least one item */ > + if (btrfs_header_nritems(eb) == 0) { > + btrfs_err(fs_info, > + "invalid tree nritems, bytenr=%llu nritems=0 expect >0", > + eb->start); > + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); > + return -EUCLEAN; > + } Shouldn't this check be before !first_key, e.g. we always want to verify that a particular node has at least 1 item ? > > /* > * For live tree block (new tree blocks in current transaction), > diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c > index 96fce4bef4e7..a4c7f7ed8490 100644 > --- a/fs/btrfs/tree-checker.c > +++ b/fs/btrfs/tree-checker.c > @@ -888,6 +888,12 @@ static int check_leaf(struct extent_buffer *leaf, bool check_item_data) > owner); > return -EUCLEAN; > } > + /* Unknown tree */ > + if (owner == 0) { > + generic_err(leaf, 0, > + "invalid owner, root 0 is not defined"); > + return -EUCLEAN; > + } > return 0; > } > >