> Sent: Friday, September 28, 2018 at 7:59 AM
> From: "Qu Wenruo" <wqu@xxxxxxxx>
> To: linux-btrfs@xxxxxxxxxxxxxxx
> Subject: [PATCH] btrfs: tree-checker: Check level for leaves and nodes
>
> Although we have tree level check at tree read runtime, it's completely
> based on its parent level.
> We still need to do accurate level check to avoid invalid tree blocks
> sneak into kernel space.
>
> The check itself is simple, for leaf its level should always be 0.
> For nodes its level should be in range [1, BTRFS_MAX_LEVEL - 1].
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Reviewed-by: Su Yue <suy.fnst@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/tree-checker.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index db835635372f..cab0b1f1f741 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -487,6 +487,13 @@ static int check_leaf(struct btrfs_fs_info *fs_info, struct extent_buffer *leaf,
> u32 nritems = btrfs_header_nritems(leaf);
> int slot;
>
> + if (btrfs_header_level(leaf) != 0) {
> + generic_err(fs_info, leaf, 0,
> + "invalid level for leaf, have %d expect 0",
> + btrfs_header_level(leaf));
> + return -EUCLEAN;
> + }
> +
> /*
> * Extent buffers from a relocation tree have a owner field that
> * corresponds to the subvolume tree they are based on. So just from an
> @@ -645,9 +652,16 @@ int btrfs_check_node(struct btrfs_fs_info *fs_info, struct extent_buffer *node)
> unsigned long nr = btrfs_header_nritems(node);
> struct btrfs_key key, next_key;
> int slot;
> + int level = btrfs_header_level(node);
> u64 bytenr;
> int ret = 0;
>
> + if (level <= 0 || level >= BTRFS_MAX_LEVEL) {
> + generic_err(fs_info, node, 0,
> + "invalid level for node, have %d expect [1, %d]",
> + level, BTRFS_MAX_LEVEL - 1);
> + return -EUCLEAN;
> + }
> if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(fs_info)) {
> btrfs_crit(fs_info,
> "corrupt node: root=%llu block=%llu, nritems too %s, have %lu expect range [1,%u]",
> --
> 2.19.0
>
>
