3.16.83-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Qu Wenruo <wqu@xxxxxxxx> commit 514c7dca85a0bf40be984dab0b477403a6db901f upstream. 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@xxxxxxxxxx> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Reviewed-by: Su Yue <suy.fnst@xxxxxxxxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> [bwh: Backported to 4.4: Use root->fs_info instead of fs_info] Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- fs/btrfs/extent-tree.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -8556,6 +8556,8 @@ static int find_first_block_group(struct 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); @@ -8590,8 +8592,32 @@ static int find_first_block_group(struct "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(root->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 { - ret = 0; + 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(root->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;
