btrfs: Check that each block group has corresponding chunk at mount time (514c7dca) · Commits · 戴 / test

A crafted btrfs image with incorrect chunk<->block group mapping will trigger a lot of unexpected things as the mapping is essential. Although the problem can be caught by block group item checker added in "btrfs: tree-checker: Verify block_group_item", it's still not sufficient. A sufficiently valid block group item can pass the check added by the mentioned patch but could fail to match the existing chunk. 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. Here we reuse the original helper find_first_block_group(), which is already doing the basic bg -> chunk checks, adding further checks of the start/len and type flags. Link: https://bugzilla.kernel.org/show_bug.cgi?id=199837 Reported-by:

Xu Wen <wen.xu@gatech.edu> Signed-off-by:

Qu Wenruo <wqu@suse.com> Reviewed-by:

Su Yue <suy.fnst@cn.fujitsu.com> Reviewed-by:

David Sterba <dsterba@suse.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

+27 −1

Original line number	Diff line number	Diff line
		@@ -9532,6 +9532,8 @@ static int find_first_block_group(struct btrfs_fs_info *fs_info,
		int ret = 0;
		struct btrfs_key found_key;
		struct extent_buffer *leaf;
		struct btrfs_block_group_item bg;
		u64 flags;
		int slot;

		ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
		@@ -9566,9 +9568,33 @@ static int find_first_block_group(struct btrfs_fs_info *fs_info,
		"logical %llu len %llu found bg but no related chunk",
		found_key.objectid, found_key.offset);
		ret = -ENOENT;
		} else if (em->start != found_key.objectid \|\|
		em->len != found_key.offset) {
		btrfs_err(fs_info,
		"block group %llu len %llu mismatch with chunk %llu len %llu",
		found_key.objectid, found_key.offset,
		em->start, em->len);
		ret = -EUCLEAN;
		} else {
		read_extent_buffer(leaf, &bg,
		btrfs_item_ptr_offset(leaf, slot),
		sizeof(bg));
		flags = btrfs_block_group_flags(&bg) &
		BTRFS_BLOCK_GROUP_TYPE_MASK;

		if (flags != (em->map_lookup->type &
		BTRFS_BLOCK_GROUP_TYPE_MASK)) {
		btrfs_err(fs_info,
		"block group %llu len %llu type flags 0x%llx mismatch with chunk type flags 0x%llx",
		found_key.objectid,
		found_key.offset, flags,
		(BTRFS_BLOCK_GROUP_TYPE_MASK &
		em->map_lookup->type));
		ret = -EUCLEAN;
		} else {
		ret = 0;
		}
		}
		free_extent_map(em);
		goto out;
		}

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