Re: [PATCH] nfsd: wrong index used in inner loop

[Andrew Morton]

On Tue, 08 Mar 2011 22:32:26 +0100
roel <roel.kluin@xxxxxxxxx> wrote:

> Index i was already used in the outer loop
> 
> Signed-off-by: Roel Kluin <roel.kluin@xxxxxxxxx>
> ---
>  fs/nfsd/nfs4xdr.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> Not 100% sure this one is needed but it looks suspicious.
> 
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 1275b86..615f0a9 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -1142,7 +1142,7 @@ nfsd4_decode_create_session(struct nfsd4_compoundargs *argp,
>  
>  	u32 dummy;
>  	char *machine_name;
> -	int i;
> +	int i, j;
>  	int nr_secflavs;
>  
>  	READ_BUF(16);
> @@ -1215,7 +1215,7 @@ nfsd4_decode_create_session(struct nfsd4_compoundargs *argp,
>  			READ_BUF(4);
>  			READ32(dummy);
>  			READ_BUF(dummy * 4);
> -			for (i = 0; i < dummy; ++i)
> +			for (j = 0; j < dummy; ++j)
>  				READ32(dummy);
>  			break;
>  		case RPC_AUTH_GSS:

ooh, big bug.

I wonder why it was not previously detected at runtime.  Perhaps
nr_secflavs is always 1.

afacit this bug will allow a well-crafted packet to cause an
infinite-until-it-oopses loop in the kernel.
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