[PATCHv2 7/9] UBIFS: do not write rubbish into truncation scanning node

[Adrian Hunter]

Artem Bityutskiy wrote:
> From: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
> 
> In the scanning code, in 'ubifs_add_snod()', we write rubbish into
> 'snod->key', because we assume that on-flash truncation nodes have a key, but
> they do not. If the other parts of UBIFS then mistakenly try to look-up
> the truncation node key (they should not do this, but may do because of a bug),
> we can succeed and corrupt TNC. It looks like we did have such a situation in
> 'sort_nodes()' in gc.c.
> 
> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
> ---
>  fs/ubifs/scan.c |    1 -
>  1 files changed, 0 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ubifs/scan.c b/fs/ubifs/scan.c
> index 96c5253..a0a305c 100644
> --- a/fs/ubifs/scan.c
> +++ b/fs/ubifs/scan.c
> @@ -212,7 +212,6 @@ int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
>  	case UBIFS_DENT_NODE:
>  	case UBIFS_XENT_NODE:
>  	case UBIFS_DATA_NODE:
> -	case UBIFS_TRUN_NODE:

There is another bug in ubifs_recover_size_accum() that expects a truncate node
to have a key.  That would be fixed by using trun_key_init() here.

>  		/*
>  		 * The key is in the same place in all keyed
>  		 * nodes.