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_krb5_unseal.c b/net/sunrpc/auth_gss/gss_krb5_unseal.c
index db055fd..0828cf6 100644
--- a/net/sunrpc/auth_gss/gss_krb5_unseal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_unseal.c
@@ -79,7 +79,8 @@
 	int			signalg;
 	int			sealalg;
 	s32			checksum_type;
-	struct xdr_netobj	md5cksum = {.len = 0, .data = NULL};
+	char			cksumdata[16];
+	struct xdr_netobj	md5cksum = {.len = 0, .data = cksumdata};
 	s32			now;
 	int			direction;
 	s32			seqnum;
@@ -176,6 +177,5 @@
 
 	ret = GSS_S_COMPLETE;
 out:
-	kfree(md5cksum.data);
 	return ret;
 }