4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Qu Wenruo <w...@suse.com> commit 7ef49515fa6727cb4b6f2f5b0ffbc5fc20a9f8c6 upstream. If a crafted image has missing block group items, it could cause unexpected behavior and breaks the assumption of 1:1 chunk<->block group mapping. Although we have the block group -> chunk mapping check, we still need chunk -> block group mapping check. This patch will do extra check to ensure each chunk has its corresponding block group. Link: https://bugzilla.kernel.org/show_bug.cgi?id=199847 Reported-by: Xu Wen <wen...@gatech.edu> Signed-off-by: Qu Wenruo <w...@suse.com> Reviewed-by: Gu Jinxiang <g...@cn.fujitsu.com> Reviewed-by: David Sterba <dste...@suse.com> Signed-off-by: David Sterba <dste...@suse.com> [bwh: Backported to 4.4: adjust context] Signed-off-by: Ben Hutchings <ben.hutchi...@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/btrfs/extent-tree.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-) --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -9765,6 +9765,62 @@ btrfs_create_block_group_cache(struct bt return cache; } + +/* + * Iterate all chunks and verify that each of them has the corresponding block + * group + */ +static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info) +{ + struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree; + struct extent_map *em; + struct btrfs_block_group_cache *bg; + u64 start = 0; + int ret = 0; + + while (1) { + read_lock(&map_tree->map_tree.lock); + /* + * lookup_extent_mapping will return the first extent map + * intersecting the range, so setting @len to 1 is enough to + * get the first chunk. + */ + em = lookup_extent_mapping(&map_tree->map_tree, start, 1); + read_unlock(&map_tree->map_tree.lock); + if (!em) + break; + + bg = btrfs_lookup_block_group(fs_info, em->start); + if (!bg) { + btrfs_err(fs_info, + "chunk start=%llu len=%llu doesn't have corresponding block group", + em->start, em->len); + ret = -EUCLEAN; + free_extent_map(em); + break; + } + if (bg->key.objectid != em->start || + bg->key.offset != em->len || + (bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK) != + (em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK)) { + btrfs_err(fs_info, +"chunk start=%llu len=%llu flags=0x%llx doesn't match block group start=%llu len=%llu flags=0x%llx", + em->start, em->len, + em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK, + bg->key.objectid, bg->key.offset, + bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK); + ret = -EUCLEAN; + free_extent_map(em); + btrfs_put_block_group(bg); + break; + } + start = em->start + em->len; + free_extent_map(em); + btrfs_put_block_group(bg); + } + return ret; +} + int btrfs_read_block_groups(struct btrfs_root *root) { struct btrfs_path *path; @@ -9951,7 +10007,7 @@ int btrfs_read_block_groups(struct btrfs } init_global_block_rsv(info); - ret = 0; + ret = check_chunk_block_group_mappings(info); error: btrfs_free_path(path); return ret;
