Re: [PATCH v3] Avoid buffer overruns by allocating buffer in svcauth_gss_validate()

[Chuck Lever <chuck.lever@oracle.com>]

On May 28, 2014, at 3:09 PM, Steve Dickson <steved@redhat.com> wrote:

> Signed-off-by: Steve Dickson <steved@redhat.com>

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>

> ---
> src/svc_auth_gss.c |   14 +++++++-------
> 1 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/src/svc_auth_gss.c b/src/svc_auth_gss.c
> index 601a691..26c1065 100644
> --- a/src/svc_auth_gss.c
> +++ b/src/svc_auth_gss.c
> @@ -286,21 +286,19 @@ svcauth_gss_validate(struct svc_rpc_gss_data *gd, struct rpc_msg *msg)
> 	struct opaque_auth	*oa;
> 	gss_buffer_desc		 rpcbuf, checksum;
> 	OM_uint32		 maj_stat, min_stat, qop_state;
> -	u_char			 rpchdr[128];
> +	u_char			 *rpchdr;
> 	int32_t			*buf;
> 
> 	gss_log_debug("in svcauth_gss_validate()");
> 
> -	memset(rpchdr, 0, sizeof(rpchdr));
> -
> 	/* XXX - Reconstruct RPC header for signing (from xdr_callmsg). */
> 	oa = &msg->rm_call.cb_cred;
> 	if (oa->oa_length > MAX_AUTH_BYTES)
> 		return (FALSE);
> -	
> -	/* 8 XDR units from the IXDR macro calls. */
> -	if (sizeof(rpchdr) < (8 * BYTES_PER_XDR_UNIT +
> -			RNDUP(oa->oa_length)))
> +
> +	rpchdr = (u_char *)calloc(((8 * BYTES_PER_XDR_UNIT) + 
> +			RNDUP(oa->oa_length)), 1);
> +	if (rpchdr == NULL)
> 		return (FALSE);
> 
> 	buf = (int32_t *)rpchdr;
> @@ -325,6 +323,8 @@ svcauth_gss_validate(struct svc_rpc_gss_data *gd, struct rpc_msg *msg)
> 	maj_stat = gss_verify_mic(&min_stat, gd->ctx, &rpcbuf, &checksum,
> 				  &qop_state);
> 
> +	free(rpchdr);
> +
> 	if (maj_stat != GSS_S_COMPLETE) {
> 		gss_log_status("gss_verify_mic", maj_stat, min_stat);
> 		return (FALSE);
> -- 
> 1.7.1
> 
> --
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com