From: Qu Wenruo Date: Tue, 3 Jul 2018 09:10:06 +0000 (+0800) Subject: btrfs: tree-checker: Detect invalid and empty essential trees X-Git-Tag: v4.19~236^2~122 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ba480dd4db9f1798541eb2d1c423fc95feee8d36;p=platform%2Fkernel%2Flinux-rpi.git btrfs: tree-checker: Detect invalid and empty essential trees A crafted image has empty root tree block, which will later cause NULL pointer dereference. The following trees should never be empty: 1) Tree root Must contain at least root items for extent tree, device tree and fs tree 2) Chunk tree Or we can't even bootstrap as it contains the mapping. 3) Fs tree At least inode item for top level inode (.). 4) Device tree Dev extents for chunks 5) Extent tree Must have corresponding extent for each chunk. If any of them is empty, we are sure the fs is corrupted and no need to mount it. Link: https://bugzilla.kernel.org/show_bug.cgi?id=199847 Reported-by: Xu Wen Signed-off-by: Qu Wenruo Tested-by: Gu Jinxiang Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 3bade2a..db83563 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -496,9 +496,22 @@ static int check_leaf(struct btrfs_fs_info *fs_info, struct extent_buffer *leaf, * skip this check for relocation trees. */ if (nritems == 0 && !btrfs_header_flag(leaf, BTRFS_HEADER_FLAG_RELOC)) { + u64 owner = btrfs_header_owner(leaf); struct btrfs_root *check_root; - key.objectid = btrfs_header_owner(leaf); + /* These trees must never be empty */ + if (owner == BTRFS_ROOT_TREE_OBJECTID || + owner == BTRFS_CHUNK_TREE_OBJECTID || + owner == BTRFS_EXTENT_TREE_OBJECTID || + owner == BTRFS_DEV_TREE_OBJECTID || + owner == BTRFS_FS_TREE_OBJECTID || + owner == BTRFS_DATA_RELOC_TREE_OBJECTID) { + generic_err(fs_info, leaf, 0, + "invalid root, root %llu must never be empty", + owner); + return -EUCLEAN; + } + key.objectid = owner; key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1;