Re: [PATCH 1/5] nfs41: fix wrong error on callback decode hdr overflow

[Trond Myklebust <Trond.Myklebust@netapp.com>]

On Wed, 2010-01-06 at 13:23 -0500, andros@netapp.com wrote: 
> From: Andy Adamson <andros@netapp.com>
> 
> decode_op_hdr returns NFS4ERR_RESOURCE on decode buffer overflow which is
> correct for v4.0. Will fix the return for v4.1 along with all the other
> NFS4ERR_RESOURCE overflow errors in a later patch.
> 
> Signed-off-by: Andy Adamson <andros@netapp.com>
> ---
>  fs/nfs/callback_xdr.c |    6 ++----
>  1 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
> index 8e1a251..e24487d 100644
> --- a/fs/nfs/callback_xdr.c
> +++ b/fs/nfs/callback_xdr.c
> @@ -605,17 +605,15 @@ static __be32 process_op(uint32_t minorversion, int nop,
>  		struct xdr_stream *xdr_out, void *resp)
>  {
>  	struct callback_op *op = &callback_ops[0];
> -	unsigned int op_nr = OP_CB_ILLEGAL;
> +	unsigned int op_nr;

This will cause us to return a random op number in the case where the
buffer overflows.

> 	__be32 status;
>  	long maxlen;
>  	__be32 res;
>  
>  	dprintk("%s: start\n", __func__);
>  	status = decode_op_hdr(xdr_in, &op_nr);
> -	if (unlikely(status)) {
> -		status = htonl(NFS4ERR_OP_ILLEGAL);
> +	if (unlikely(status))
>  		goto out;
> -	}
>  
>  	dprintk("%s: minorversion=%d nop=%d op_nr=%u\n",
>  		__func__, minorversion, nop, op_nr);

The correct thing to do would appear to be rather to set
NFS4ERR_RESOURCE in the CB_COMPOUND return value, and simply not to
return an op here at all.

Trond