NFSv4.1: Fix a kfree() of uninitialised pointers in decode_cb_sequence_args

commit d8ba1f97 upstream.

If the call to decode_rc_list() fails due to a memory allocation error,
then we need to truncate the array size to ensure that we only call
kfree() on those pointer that were allocated.
Reported-by: David Ramos <daramos@stanford.edu>
Fixes: 4aece6a1 ("nfs41: cb_sequence xdr implementation")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

fs/nfs/callback_xdr.c

@@ -464,10 +464,12 @@ static __be32 decode_cb_sequence_args(struct svc_rqst *rqstp,
 
 		for (i = 0; i < args->csa_nrclists; i++) {
 			status = decode_rc_list(xdr, &args->csa_rclists[i]);
-			if (status)
+			if (status) {
+				args->csa_nrclists = i;
 				goto out_free;
 			}
 		}
+	}
 	status = 0;
 
 	dprintk("%s: sessionid %x:%x:%x:%x sequenceid %u slotid %u "