On Thu, Aug 22, 2019 at 10:14:15AM +0800, 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 <wqu@xxxxxxxx> Added to misc-next, thanks.
