On 2018年08月01日 20:12, Nikolay Borisov wrote: > > > On 1.08.2018 14:13, Qu Wenruo wrote: >> >> >> On 2018年08月01日 18:08, Nikolay Borisov wrote: >>> >>> >>> On 1.08.2018 11:08, Qu Wenruo wrote: >>>> [BUG] >>>> When mounting certain crafted image, btrfs will trigger kernel BUG_ON() >>>> when try to recover balance: >>>> ------ >>>> ------------[ cut here ]------------ >>>> kernel BUG at fs/btrfs/extent-tree.c:8956! >>>> invalid opcode: 0000 [#1] PREEMPT SMP NOPTI >>>> CPU: 1 PID: 662 Comm: mount Not tainted 4.18.0-rc1-custom+ #10 >>>> RIP: 0010:walk_up_proc+0x336/0x480 [btrfs] >>>> RSP: 0018:ffffb53540c9b890 EFLAGS: 00010202 >>>> Call Trace: >>>> walk_up_tree+0x172/0x1f0 [btrfs] >>>> btrfs_drop_snapshot+0x3a4/0x830 [btrfs] >>>> merge_reloc_roots+0xe1/0x1d0 [btrfs] >>>> btrfs_recover_relocation+0x3ea/0x420 [btrfs] >>>> open_ctree+0x1af3/0x1dd0 [btrfs] >>>> btrfs_mount_root+0x66b/0x740 [btrfs] >>>> mount_fs+0x3b/0x16a >>>> vfs_kern_mount.part.9+0x54/0x140 >>>> btrfs_mount+0x16d/0x890 [btrfs] >>>> mount_fs+0x3b/0x16a >>>> vfs_kern_mount.part.9+0x54/0x140 >>>> do_mount+0x1fd/0xda0 >>>> ksys_mount+0xba/0xd0 >>>> __x64_sys_mount+0x21/0x30 >>>> do_syscall_64+0x60/0x210 >>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe >>>> ---[ end trace d4344e4deee03435 ]--- >>>> ------ >>>> >>>> [CAUSE] >>>> Another extent tree corruption. >>>> >>>> In this particular case, tree reloc root's owner is >>>> DATA_RELOC_TREE (should be TREE_RELOC_TREE), thus its backref is >>>> corrupted and we failed the owner check in walk_up_tree(). >>>> >>>> [FIX] >>>> It's pretty hard to take care of every extent tree corruption, but at >>>> least we can remove such BUG_ON() and exit more gracefully. >>>> >>>> And since in this particular image, DATA_RELOC_TREE and TREE_RELOC_TREE >>>> shares the same root (which is obviously invalid), we needs to make >>>> __del_reloc_root() more robust to detect such invalid share to avoid >>>> possible NULL dereference as root->node can be NULL in this case. >>>> >>>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=200411 >>>> Reported-by: Xu Wen <wen.xu@xxxxxxxxxx> >>>> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> >>>> --- >>>> As always, the patch is also pushed to my github repo, along with other >>>> fuzzed images related fixes: >>>> https://github.com/adam900710/linux/tree/tree_checker_enhance >>>> (BTW, is it correct to indicate a branch like above?) >>>> --- >>>> fs/btrfs/extent-tree.c | 27 +++++++++++++++++++-------- >>>> fs/btrfs/relocation.c | 2 +- >>>> 2 files changed, 20 insertions(+), 9 deletions(-) >>>> >>>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c >>>> index da615ebc072e..5f4ca61348b5 100644 >>>> --- a/fs/btrfs/extent-tree.c >>>> +++ b/fs/btrfs/extent-tree.c >>>> @@ -8949,17 +8949,26 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans, >>>> } >>>> >>>> if (eb == root->node) { >>>> - if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) >>>> + if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) { >>>> parent = eb->start; >>>> - else >>>> - BUG_ON(root->root_key.objectid != >>>> - btrfs_header_owner(eb)); >>>> + } else if (root->root_key.objectid != btrfs_header_owner(eb)) { >>>> + btrfs_err_rl(fs_info, >>>> + "unexpected tree owner, have %llu expect %llu", >>>> + btrfs_header_owner(eb), >>>> + root->root_key.objectid); >>>> + return -EINVAL; >>> >>> EINVAL or ECLEANUP? >> >> Yep, also my concern here. >> >> I have no bias here, and both makes its sense here. >> >> EUCLEAN means it's something unexpected, but normally it's used in >> static check, no sure if it suits for runtime check. > > My thinking goes if something is an on-disk error (and fuzzed images > fall in that category) then we should return EUCLEAN. If the owner can > be mismatched only as a result of erroneous data on-disk which is then > read and subsequently this code triggers then it's something induced due > to an on-disk error. Makes sense. Does it also mean later BUG_ON() convert would also use EUCLEAN as most BUG_ON() is either some real bug or corrupted/fuzzed images? Thanks, Qu > >> >> Although EINVAL looks more suitable for runtime error, it is not a >> perfect errno either, as it's not something invalid from user, but the >> fs has something unexpected. >> >> I'm all ears on this errno issue. >> >> Thanks, >> Qu >> >>> >>>> + } >>>> } else { >>>> - if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF) >>>> + if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF) { >>>> parent = path->nodes[level + 1]->start; >>>> - else >>>> - BUG_ON(root->root_key.objectid != >>>> - btrfs_header_owner(path->nodes[level + 1])); >>>> + } else if (root->root_key.objectid != >>>> + btrfs_header_owner(path->nodes[level + 1])) { >>>> + btrfs_err_rl(fs_info, >>>> + "unexpected tree owner, have %llu expect %llu", >>>> + btrfs_header_owner(eb), >>>> + root->root_key.objectid); >>>> + return -EINVAL; >>> ditto >>>> + } >>>> } >>>> >>>> btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1); >>>> @@ -9020,6 +9029,8 @@ static noinline int walk_up_tree(struct btrfs_trans_handle *trans, >>>> ret = walk_up_proc(trans, root, path, wc); >>>> if (ret > 0) >>>> return 0; >>>> + if (ret < 0) >>>> + return ret; >>>> >>>> if (path->locks[level]) { >>>> btrfs_tree_unlock_rw(path->nodes[level], >>>> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c >>>> index a2fc0bd83a40..c64051d33d05 100644 >>>> --- a/fs/btrfs/relocation.c >>>> +++ b/fs/btrfs/relocation.c >>>> @@ -1321,7 +1321,7 @@ static void __del_reloc_root(struct btrfs_root *root) >>>> struct mapping_node *node = NULL; >>>> struct reloc_control *rc = fs_info->reloc_ctl; >>>> >>>> - if (rc) { >>>> + if (rc && root->node) { >>>> spin_lock(&rc->reloc_root_tree.lock); >>>> rb_node = tree_search(&rc->reloc_root_tree.rb_root, >>>> root->node->start); >>>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
