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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 57A66C43381 for ; Tue, 12 Mar 2019 11:10:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25412206DF for ; Tue, 12 Mar 2019 11:10:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726255AbfCLLKE (ORCPT ); Tue, 12 Mar 2019 07:10:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:50478 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725811AbfCLLKD (ORCPT ); Tue, 12 Mar 2019 07:10:03 -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 AC340AD47; Tue, 12 Mar 2019 11:10:00 +0000 (UTC) Subject: Re: [PATCH v2] btrfs: Check the first key and level for cached extent buffer To: Nikolay Borisov , linux-btrfs@vger.kernel.org Cc: Yoon Jungyeon References: <20190312091040.3352-1-wqu@suse.com> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=wqu@suse.de; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0F1F1IFdlbnJ1byA8d3F1QHN1c2UuZGU+iQFUBBMBCAA+AhsDBQsJCAcCBhUICQoLAgQW AgMBAh4BAheAFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlnVgp0FCQlmAm4ACgkQwj2R86El /qilmgf/cUq9kFQo577ku5gc6rFpVg68ublBwjYpwjw0b//xo+Wo1wm+RRbUGs+djSZAqw12 D4F3r0mBTI7abUCNWAbFkYZSAIFVi0DMkjypIVS7PSaEt04rM9VBTToE+YqU6WENeJ57R2p2 +hI0wZrBwxObdsdaOtxWtsp3bmhIbdqxSKrtXuRawy4KnQYcLuGzOce9okdlbAE0W3KHm1gQ oNAe6FX8nC9qo14m8LqEbThYH+qj4iCMlN8HIfbSx4F3e7nHZ+UAMW+E/lnMRkIB9Df+JyVd /NlXzIjZAggcWsqpx6D4wyAuexKWkiGQeUeArUNihAwXjmyqWPGmjVyIh+oC6LkBDQRZ1YGv AQgAqlPrYeBLMv3PAZ75YhQIwH6c4SNcB++hQ9TCT5gIQNw51+SQzkXIGgmzxMIS49cZcE4K Xk/kHw5hieQeQZa60BWVRNXwoRI4ib8okgDuMkD5Kz1WEyO149+BZ7HD4/yK0VFJGuvDJR8T 7RZwB69uVSLjkuNZZmCmDcDzS0c/SJOg5nkxt1iTtgUETb1wNKV6yR9XzRkrEW/qShChyrS9 fNN8e9c0MQsC4fsyz9Ylx1TOY/IF/c6rqYoEEfwnpdlz0uOM1nA1vK+wdKtXluCa79MdfaeD /dt76Kp/o6CAKLLcjU1Iwnkq1HSrYfY3HZWpvV9g84gPwxwxX0uXquHxLwARAQABiQE8BBgB CAAmFiEELd9y5aWlW6idqkLhwj2R86El/qgFAlnVga8CGwwFCQPCZwAACgkQwj2R86El/qgN 8Qf+M0vM2Idwm5txZZSs+/kSgcPxEwYmxUinnUJGyc0ZWYQXPl0cBetZon9El0naijGzNWvf HxIPB+ZFehk6Otgc78p1a3/xck/s1myFRLrmbbTJNoFiyL25ljcq0J8z5Zp4yuABL2RiLdaZ Pt/jfwjBHwGR+QKp6dD2qMrUWf9b7TFzYDMZXzZ2/eoIgtyjEelNBPrIgOFe24iKMjaGjd97 fJuRcBMHdhUAxvXQF1oRtd83JvYJ5OtwTd8MgkEfl+fo7HwWkuHbzc70L4fFKv2BowqFdaHy mId1ijGPGr46tuZ5a4cw/zbaPYx6fJ4sK9tSv/6V1QPNUdqml6hm6pfs6A== Message-ID: Date: Tue, 12 Mar 2019 19:09:50 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: 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 2019/3/12 下午7:07, Nikolay Borisov wrote: > > > On 12.03.19 г. 11:10 ч., Qu Wenruo wrote: >> [BUG] >> When reading a file from a fuzzed image, kernel can panic like: >> BTRFS warning (device loop0): csum failed root 5 ino 270 off 0 csum 0x98f94189 expected csum 0x00000000 mirror 1 >> assertion failed: !memcmp_extent_buffer(b, &disk_key, offsetof(struct btrfs_leaf, items[0].key), sizeof(disk_key)), file: fs/btrfs/ctree.c, line: 2544 >> ------------[ cut here ]------------ >> kernel BUG at fs/btrfs/ctree.h:3500! >> invalid opcode: 0000 [#1] PREEMPT SMP NOPTI >> RIP: 0010:btrfs_search_slot.cold.24+0x61/0x63 [btrfs] >> Call Trace: >> btrfs_lookup_csum+0x52/0x150 [btrfs] >> __btrfs_lookup_bio_sums+0x209/0x640 [btrfs] >> btrfs_submit_bio_hook+0x103/0x170 [btrfs] >> submit_one_bio+0x59/0x80 [btrfs] >> extent_read_full_page+0x58/0x80 [btrfs] >> generic_file_read_iter+0x2f6/0x9d0 >> __vfs_read+0x14d/0x1a0 >> vfs_read+0x8d/0x140 >> ksys_read+0x52/0xc0 >> do_syscall_64+0x60/0x210 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> >> [CAUSE] >> The fuzzed image has a corrupted leaf whose first key doesn't match with its parent: >> checksum tree key (CSUM_TREE ROOT_ITEM 0) >> node 29741056 level 1 items 14 free 107 generation 19 owner CSUM_TREE >> fs uuid 3381d111-94a3-4ac7-8f39-611bbbdab7e6 >> chunk uuid 9af1c3c7-2af5-488b-8553-530bd515f14c >> ... >> key (EXTENT_CSUM EXTENT_CSUM 79691776) block 29761536 gen 19 >> >> leaf 29761536 items 1 free space 1726 generation 19 owner CSUM_TREE >> leaf 29761536 flags 0x1(WRITTEN) backref revision 1 >> fs uuid 3381d111-94a3-4ac7-8f39-611bbbdab7e6 >> chunk uuid 9af1c3c7-2af5-488b-8553-530bd515f14c >> item 0 key (EXTENT_CSUM EXTENT_CSUM 8798638964736) itemoff 1751 itemsize 2244 >> range start 8798638964736 end 8798641262592 length 2297856 >> >> When reading above tree block, we have extent_buffer->refs = 2 in the >> context: >> - initial one from __alloc_extent_buffer() >> alloc_extent_buffer() >> |- __alloc_extent_buffer() >> |- atomic_set(&eb->refs, 1) >> >> - one being added to fs_info->buffer_radix >> alloc_extent_buffer() >> |- check_buffer_tree_ref() >> |- atomic_inc(&eb->refs) >> >> So even we call free_extent_buffer() in read_tree_block or other similar >> situation, we only decrease the refs by 1, it doesn't reach 0 and won't >> be freed right now. >> >> The staled eb and its corrupted content will still be kept cached. >> >> Further more, we have several extra cases where we either don't do >> first key check or the check is not proper for all callers: >> - scrub >> We just don't have first key in this context. >> >> - shared tree block >> One tree block can be shared by several snapshot/subvolume trees. >> In that case, the first key check for one subvolume doesn't apply to >> another. >> >> So for above reasons, a corrupted extent buffer can sneak into the >> buffer cache. >> >> [FIX] >> Export verify_level_key() as btrfs_verify_level_key() and call it in >> read_block_for_search() to fill the hole. >> >> Due to above described reasons, even we can free corrupted extent buffer >> from cache, we still need the check in read_block_for_search(), for >> scrub and shared tree blocks. >> >> Reported-by: Yoon Jungyeon >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=202755 >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=202757 >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=202759 >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=202761 >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=202767 >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=202769 >> Signed-off-by: Qu Wenruo >> --- >> changelog: >> v2: >> - Commit message update to show the reason why stale ebs are kept in >> cache. >> - Commit message update to show extra reasons why we still need the >> check, mainly for scrub and shared tree blocks. >> --- >> fs/btrfs/ctree.c | 10 ++++++++++ >> fs/btrfs/disk-io.c | 10 +++++----- >> fs/btrfs/disk-io.h | 3 +++ >> 3 files changed, 18 insertions(+), 5 deletions(-) >> >> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c >> index 5a6c39b44c84..7672932aa5b4 100644 >> --- a/fs/btrfs/ctree.c >> +++ b/fs/btrfs/ctree.c >> @@ -2401,6 +2401,16 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, >> if (tmp) { >> /* first we do an atomic uptodate check */ >> if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) { >> + /* >> + * Do extra check for first_key, eb can be stale due to >> + * being cached, read from scrub, or have multiple >> + * parents (shared tree blocks). >> + */ >> + if (btrfs_verify_level_key(fs_info, tmp, >> + parent_level - 1, &first_key, gen)) { >> + free_extent_buffer(tmp); >> + return -EUCLEAN; >> + } > > What about verify_parent_transid? Shouldn't it also be checked here? Previous btrfs_buffer_uptodate() call implies verify_parent_transid() check, and that's why btrfs_buffer_uptodate() needs transid parameter. Thanks, Qu > >> *eb_ret = tmp; >> return 0; >> } >> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >> index 298b34721bc0..e2a0cb362d28 100644 >> --- a/fs/btrfs/disk-io.c >> +++ b/fs/btrfs/disk-io.c >> @@ -423,9 +423,9 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info, >> return ret; >> } >> >> -static int verify_level_key(struct btrfs_fs_info *fs_info, >> - struct extent_buffer *eb, int level, >> - struct btrfs_key *first_key, u64 parent_transid) >> +int btrfs_verify_level_key(struct btrfs_fs_info *fs_info, >> + struct extent_buffer *eb, int level, >> + struct btrfs_key *first_key, u64 parent_transid) >> { >> int found_level; >> struct btrfs_key found_key; >> @@ -500,8 +500,8 @@ static int btree_read_extent_buffer_pages(struct btrfs_fs_info *fs_info, >> if (verify_parent_transid(io_tree, eb, >> parent_transid, 0)) >> ret = -EIO; >> - else if (verify_level_key(fs_info, eb, level, >> - first_key, parent_transid)) >> + else if (btrfs_verify_level_key(fs_info, eb, level, >> + first_key, parent_transid)) >> ret = -EUCLEAN; >> else >> break; >> diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h >> index 987a64bc0c66..67a9fe2d29c7 100644 >> --- a/fs/btrfs/disk-io.h >> +++ b/fs/btrfs/disk-io.h >> @@ -39,6 +39,9 @@ static inline u64 btrfs_sb_offset(int mirror) >> struct btrfs_device; >> struct btrfs_fs_devices; >> >> +int btrfs_verify_level_key(struct btrfs_fs_info *fs_info, >> + struct extent_buffer *eb, int level, >> + struct btrfs_key *first_key, u64 parent_transid); >> struct extent_buffer *read_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr, >> u64 parent_transid, int level, >> struct btrfs_key *first_key); >>