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Thu, 25 Jul 2019 06:49:01 +0000 (UTC) Subject: Re: [PATCH v2 0/5] btrfs: Enhanced runtime defence against fuzzed images To: Qu Wenruo , linux-btrfs@vger.kernel.org Cc: Jungyeon Yoon References: <20190725061222.9581-1-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: <1c212f70-4863-7bcc-be23-893d145bff58@suse.com> Date: Thu, 25 Jul 2019 09:49:00 +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: <20190725061222.9581-1-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: > Another wave of defence enhancment, including: > > - Enhanced eb accessors > Not really needed for the fuzzed images, as 448de471cd4c > ("btrfs: Check the first key and level for cached extent buffer") > already fixed half of the reported images. > Just add a final layer of safe net. > > Just to complain here, two experienced btrfs developer have got > confused by @start, @len in functions like read_extent_buffer() with > logical address. > The best example to solve the confusion is to check the > read_extent_buffer() call in btree_read_extent_buffer_pages(). > > I'm not sure why this confusion happens or even get spread. > My guess is the extent_buffer::start naming causing the problem. > > If so, I would definitely rename extent_buffer::start to > extent_buffer::bytenr at any cost. > Hopes the new commend will address the problem for now. it should either be bytenr or disk_bytenr or disk_addr or address. Looking at the code base though, it seems there is already a convention that bytenr means the byte number in the logical address space. So indeed, bytenr should be ok. > > - BUG_ON() hunt in __btrfs_free_extent() > Kill BUG_ON()s in __btrfs_free_extent(), replace with error reporting > and why it shouldn't happen. > > Also add comment on what __btrfs_free_extent() is designed to do, with > two dump-tree examples for newcomers. > > - BUG_ON() hunt in __btrfs_inc_extent_ref() > Just like __btrfs_free_extent(), but less comment as > comment for __btrfs_free_extent() should also work for > __btrfs_inc_extent_ref(), and __btrfs_inc_extent_ref() has a better > structure than __btrfs_free_extent(). > > - Defence against unbalanced empty leaf > > - Defence against bad key order across two tree blocks > > The last two cases can't be rejected by tree-checker and they are all > cross-eb cases. > Thankfully we can reuse existing first_key check against unbalanced > empty leaf, but needs extra check deep into ctree.c for tree block > merging time check. > > Reported-by: Jungyeon Yoon > [ Not to mail bombarding the report, thus only RB tag in cover letter ] > > Changelog: > v2: > - Remove duplicated error message in WARN() call. > Changed to WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)) > Also move WARN() after btrfs error message. > > - Fix a comment error in __btrfs_free_extent() > It's not adding refs to a tree block, but adding the same refs > to an existing tree block ref. > It's impossible a btrfs tree owning the same tree block directly twice. > > - Add comment for eb accessors about @start and @len > If anyone could tell me why such confusion between @start @len and > logical address is here, I will definitely solve the root cause no > matter how many codes need to be modified. > > - Use bool to replace int where only two values are returned > Also rename to follow the bool type. > > - Remove one unrelated change for the error handler in > btrfs_inc_extent_ref() > > - Add Reviewed-by tag > > Qu Wenruo (5): > btrfs: extent_io: Do extra check for extent buffer read write > functions > btrfs: extent-tree: Kill BUG_ON() in __btrfs_free_extent() and do > better comment > btrfs: Detect unbalanced tree with empty leaf before crashing btree > operations > btrfs: extent-tree: Kill the BUG_ON() in > insert_inline_extent_backref() > btrfs: ctree: Checking key orders before merged tree blocks > > fs/btrfs/ctree.c | 68 +++++++++++++++++ > fs/btrfs/disk-io.c | 8 ++ > fs/btrfs/extent-tree.c | 164 ++++++++++++++++++++++++++++++++++++---- > fs/btrfs/extent_io.c | 76 ++++++++++--------- > fs/btrfs/tree-checker.c | 6 ++ > 5 files changed, 271 insertions(+), 51 deletions(-) >