> -----Original Message----- > From: linux-btrfs-owner@xxxxxxxxxxxxxxx [mailto:linux-btrfs-owner@xxxxxxxxxxxxxxx] On Behalf Of Qu Wenruo > Sent: Tuesday, July 03, 2018 5:10 PM > To: linux-btrfs@xxxxxxxxxxxxxxx > Subject: [PATCH 4/5] btrfs: Check each block group has corresponding chunk at mount time > > A crafted btrfs with incorrect chunk<->block group mapping, it could leads > to a lot of unexpected behavior. > > Although the crafted image can be catched by block group item checker > added in "[PATCH] btrfs: tree-checker: Verify block_group_item", if one > crafted a valid enough block group item which can pass above check but > still mismatch with existing chunk, it could cause a lot of undefined > behavior. > > This patch will add extra block group -> chunk mapping check, to ensure > we have a completely matching (start, len, flags) chunk for each block > group at mount time. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=199837 > Reported-by: Xu Wen <wen.xu@xxxxxxxxxx> > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> > --- > fs/btrfs/extent-tree.c | 55 ++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 53 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 3d9fe58c0080..82b446f014b9 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -10003,6 +10003,41 @@ btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info, > return cache; > } > > +static int check_exist_chunk(struct btrfs_fs_info *fs_info, u64 start, u64 len, > + u64 flags) > +{ > + struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree; > + struct extent_map *em; > + int ret; > + > + read_lock(&map_tree->map_tree.lock); > + em = lookup_extent_mapping(&map_tree->map_tree, start, len); > + read_unlock(&map_tree->map_tree.lock); > + > + if (!em) { > + btrfs_err_rl(fs_info, > + "block group start=%llu len=%llu doesn't have corresponding chunk", > + start, len); > + ret = -ENOENT; > + goto out; > + } This check has been done in find_first_block_group which has been called before check_exist_chunk be called. > + if (em->start != start || em->len != len || > + (em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK) != > + (flags & BTRFS_BLOCK_GROUP_TYPE_MASK)) { > + btrfs_err_rl(fs_info, > +"block group start=%llu len=%llu flags=0x%llx doesn't match with chunk start=%llu len=%llu flags=0x%llx", > + start, len , flags & BTRFS_BLOCK_GROUP_TYPE_MASK, > + em->start, em->len, em->map_lookup->type & > + BTRFS_BLOCK_GROUP_TYPE_MASK); > + ret = -EUCLEAN; > + goto out; > + } Should this check also be added to find_first_block_group? > + ret = 0; > +out: > + free_extent_map(em); > + return ret; > +} > + > int btrfs_read_block_groups(struct btrfs_fs_info *info) > { > struct btrfs_path *path; > @@ -10036,6 +10071,9 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) > need_clear = 1; > > while (1) { > + struct btrfs_block_group_item bg; > + int slot; > + > ret = find_first_block_group(info, path, &key); > if (ret > 0) > break; > @@ -10043,7 +10081,20 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) > goto error; > > leaf = path->nodes[0]; > - btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); > + slot = path->slots[0]; > + btrfs_item_key_to_cpu(leaf, &found_key, slot); > + > + read_extent_buffer(leaf, &bg, btrfs_item_ptr_offset(leaf, slot), > + sizeof(bg)); > + /* > + * Chunk and block group must have 1:1 mapping. > + * So there must be a chunk for this block group. > + */ > + ret = check_exist_chunk(info, found_key.objectid, > + found_key.offset, > + btrfs_block_group_flags(&bg)); > + if (ret < 0) > + goto error; > > cache = btrfs_create_block_group_cache(info, found_key.objectid, > found_key.offset); > @@ -10068,7 +10119,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) > } > > read_extent_buffer(leaf, &cache->item, > - btrfs_item_ptr_offset(leaf, path->slots[0]), > + btrfs_item_ptr_offset(leaf, slot), > sizeof(cache->item)); > cache->flags = btrfs_block_group_flags(&cache->item); > if (!mixed && > -- > 2.18.0 > > -- > 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 > ?韬{.n?????%??檩??w?{.n???{饼?~镶?^n?■???h?璀?｛?夸z罐?+€?zf＂?????i?????_璁?:+v??撸?
