SUNRPC,RPCSEC_GSS: remove unnecessary kmalloc of a checksum

Remove unnecessary kmalloc of temporary space to hold the md5 result; it's
small enough to just put on the stack.

This code may be called to process rpc's necessary to perform writes, so
there's a potential deadlock whenever we kmalloc() here.  After this a
couple kmalloc()'s still remain, to be removed soon.

This also fixes a rare double-free on error noticed by coverity.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/auth_gss/gss_spkm3_seal.c b/net/sunrpc/auth_gss/gss_spkm3_seal.c
index 86fbf7c..18c7862 100644
--- a/net/sunrpc/auth_gss/gss_spkm3_seal.c
+++ b/net/sunrpc/auth_gss/gss_spkm3_seal.c
@@ -57,7 +57,8 @@
 {
 	s32			checksum_type;
 	char			tokhdrbuf[25];
-	struct xdr_netobj	md5cksum = {.len = 0, .data = NULL};
+	char			cksumdata[16];
+	struct xdr_netobj	md5cksum = {.len = 0, .data = cksumdata};
 	struct xdr_netobj	mic_hdr = {.len = 0, .data = tokhdrbuf};
 	int			tokenlen = 0;
 	unsigned char		*ptr;
@@ -115,13 +116,11 @@
 		dprintk("RPC: gss_spkm3_seal: SPKM_WRAP_TOK not supported\n");
 		goto out_err;
 	}
-	kfree(md5cksum.data);
 
 	/* XXX need to implement sequence numbers, and ctx->expired */
 
 	return  GSS_S_COMPLETE;
 out_err:
-	kfree(md5cksum.data);
 	token->data = NULL;
 	token->len = 0;
 	return GSS_S_FAILURE;