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Wed, 13 Mar 2019 09:19:09 +0000 (UTC) Subject: Re: [PATCH 2/6] btrfs: tree-checker: Verify dev item To: Qu Wenruo , linux-btrfs@vger.kernel.org Cc: Yoon Jungyeon References: <20190313085511.23540-1-wqu@suse.com> <20190313085511.23540-3-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: Date: Wed, 13 Mar 2019 11:19:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190313085511.23540-3-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 13.03.19 г. 10:55 ч., Qu Wenruo wrote: > [BUG] > For fuzzed image whose DEV_ITEM has invalid total_bytes as 0, then > kernel will just panic: > BUG: unable to handle kernel NULL pointer dereference at 0000000000000098 > #PF error: [normal kernel read fault] > PGD 800000022b2bd067 P4D 800000022b2bd067 PUD 22b2bc067 PMD 0 > Oops: 0000 [#1] SMP PTI > CPU: 0 PID: 1106 Comm: mount Not tainted 5.0.0-rc8+ #9 > RIP: 0010:btrfs_verify_dev_extents+0x2a5/0x5a0 > Call Trace: > open_ctree+0x160d/0x2149 > btrfs_mount_root+0x5b2/0x680 > > [CAUSE] > If device extent verification finds a deivce with 0 total_bytes, then it > assumes it's a seed dummy, then search for seed devices. > > But in this case, there is no seed device at all, causing NULL pointer. > > [FIX] > Since this is caused by fuzzed image, let's go the tree-check way, just > add a new verification for device item. > > Reported-by: Yoon Jungyeon > Link: https://bugzilla.kernel.org/show_bug.cgi?id=202691 > Signed-off-by: Qu Wenruo I had already reviewed the earlier posting of this patch so: Reviewed-by: Nikolay Borisov > --- > fs/btrfs/tree-checker.c | 84 +++++++++++++++++++++++++++++++++++++++++ > fs/btrfs/volumes.c | 9 ----- > fs/btrfs/volumes.h | 9 +++++ > 3 files changed, 93 insertions(+), 9 deletions(-) > > diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c > index fe3f37c23c29..5ccb4be583ea 100644 > --- a/fs/btrfs/tree-checker.c > +++ b/fs/btrfs/tree-checker.c > @@ -594,6 +594,87 @@ int btrfs_check_chunk_valid(struct btrfs_fs_info *fs_info, > return 0; > } > > + > +__printf(4, 5) > +__cold > +static void dev_item_err(const struct btrfs_fs_info *fs_info, > + const struct extent_buffer *eb, int slot, > + const char *fmt, ...) > +{ > + struct btrfs_key key; > + struct va_format vaf; > + va_list args; > + > + btrfs_item_key_to_cpu(eb, &key, slot); > + va_start(args, fmt); > + > + vaf.fmt = fmt; > + vaf.va = &args; > + > + btrfs_crit(fs_info, > + "corrupt %s: root=%llu block=%llu slot=%d devid=%llu %pV", > + btrfs_header_level(eb) == 0 ? "leaf" : "node", > + btrfs_header_owner(eb), btrfs_header_bytenr(eb), slot, > + key.objectid, &vaf); > + va_end(args); > +} > + > +static int check_dev_item(struct btrfs_fs_info *fs_info, > + struct extent_buffer *leaf, > + struct btrfs_key *key, int slot) > +{ > + struct btrfs_dev_item *ditem; > + u64 max_devid = max(BTRFS_MAX_DEVS(fs_info), BTRFS_MAX_DEVS_SYS_CHUNK); > + > + if (key->objectid != BTRFS_DEV_ITEMS_OBJECTID) { > + dev_item_err(fs_info, leaf, slot, > + "invalid objectid: has=%llu expect=%llu", > + key->objectid, BTRFS_DEV_ITEMS_OBJECTID); > + goto error; > + } > + if (key->offset > max_devid) { > + dev_item_err(fs_info, leaf, slot, > + "invalid devid: has=%llu expect=[0, %llu]", > + key->offset, max_devid); > + goto error; > + } > + ditem = btrfs_item_ptr(leaf, slot, struct btrfs_dev_item); > + if (btrfs_device_id(leaf, ditem) != key->offset) { > + dev_item_err(fs_info, leaf, slot, > + "devid mismatch: key has=%llu item has=%llu", > + key->offset, btrfs_device_id(leaf, ditem)); > + goto error; > + } > + > + /* > + * Since btrfs device add doesn't check device size at all, we could > + * have device item whose size is smaller than 1M which is useless, but > + * still valid. > + * So here we can only check the obviously wrong case. > + */ > + if (btrfs_device_total_bytes(leaf, ditem) == 0) { > + dev_item_err(fs_info, leaf, slot, > + "invalid total bytes: have 0"); > + goto error; > + } > + if (btrfs_device_bytes_used(leaf, ditem) > > + btrfs_device_total_bytes(leaf, ditem)) { > + dev_item_err(fs_info, leaf, slot, > + "invalid bytes used: have %llu expect [0, %llu]", > + btrfs_device_bytes_used(leaf, ditem), > + btrfs_device_total_bytes(leaf, ditem)); > + goto error; > + } > + /* > + * Remaining members like io_align/type/gen/dev_group aren't really > + * utilized. > + * Skip them to make later usage of them easier. > + */ > + return 0; > +error: > + return -EUCLEAN; > +} > + > /* > * Common point to switch the item-specific validation. > */ > @@ -624,6 +705,9 @@ static int check_leaf_item(struct btrfs_fs_info *fs_info, > ret = btrfs_check_chunk_valid(fs_info, leaf, chunk, > key->offset); > break; > + case BTRFS_DEV_ITEM_KEY: > + ret = check_dev_item(fs_info, leaf, key, slot); > + break; > } > return ret; > } > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 0e3822870f1e..0b839ecbe73f 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -4964,15 +4964,6 @@ static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type) > btrfs_set_fs_incompat(info, RAID56); > } > > -#define BTRFS_MAX_DEVS(info) ((BTRFS_MAX_ITEM_SIZE(info) \ > - - sizeof(struct btrfs_chunk)) \ > - / sizeof(struct btrfs_stripe) + 1) > - > -#define BTRFS_MAX_DEVS_SYS_CHUNK ((BTRFS_SYSTEM_CHUNK_ARRAY_SIZE \ > - - 2 * sizeof(struct btrfs_disk_key) \ > - - 2 * sizeof(struct btrfs_chunk)) \ > - / sizeof(struct btrfs_stripe) + 1) > - > static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans, > u64 start, u64 type) > { > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h > index ed806649a473..481c012eae79 100644 > --- a/fs/btrfs/volumes.h > +++ b/fs/btrfs/volumes.h > @@ -258,6 +258,15 @@ struct btrfs_fs_devices { > > #define BTRFS_BIO_INLINE_CSUM_SIZE 64 > > +#define BTRFS_MAX_DEVS(info) ((BTRFS_MAX_ITEM_SIZE(info) \ > + - sizeof(struct btrfs_chunk)) \ > + / sizeof(struct btrfs_stripe) + 1) > + > +#define BTRFS_MAX_DEVS_SYS_CHUNK ((BTRFS_SYSTEM_CHUNK_ARRAY_SIZE \ > + - 2 * sizeof(struct btrfs_disk_key) \ > + - 2 * sizeof(struct btrfs_chunk)) \ > + / sizeof(struct btrfs_stripe) + 1) > + > /* > * we need the mirror number and stripe index to be passed around > * the call chain while we are processing end_io (especially errors). >