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btrfs: Verify that every chunk has corresponding block group at mount time 

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.xu@gatech.edu>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2018-08-01 10:37:17 +08:00 committed by David Sterba
parent 514c7dca85
commit 7ef49515fa
1 changed files with 57 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
fs/btrfs/extent-tree.c
View File

@ -9844,6 +9844,62 @@ btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info,
return cache; 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_fs_info *info) int btrfs_read_block_groups(struct btrfs_fs_info *info)
{ {
struct btrfs_path *path; struct btrfs_path *path;
@ -10010,7 +10066,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
btrfs_add_raid_kobjects(info); btrfs_add_raid_kobjects(info);
init_global_block_rsv(info); init_global_block_rsv(info);
ret = 0; ret = check_chunk_block_group_mappings(info);
error: error:
btrfs_free_path(path); btrfs_free_path(path);
return ret; return ret;