[PATCH 4.4 61/93] svc: Avoid garbage replies when pc_func() returns rpc_drop_reply

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chuck Lever <chuck.lever@xxxxxxxxxx>

commit 0533b13072f4bf35738290d2cf9e299c7bc6c42a upstream.

If an RPC program does not set vs_dispatch and pc_func() returns
rpc_drop_reply, the server sends a reply anyway containing a single
word containing the value RPC_DROP_REPLY (in network byte-order, of
course). This is a nonsense RPC message.

Fixes: 9e701c610923 ("svcrpc: simpler request dropping")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Tested-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/sunrpc/svc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1188,7 +1188,8 @@ svc_process_common(struct svc_rqst *rqst
 		*statp = procp->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
 
 		/* Encode reply */
-		if (test_bit(RQ_DROPME, &rqstp->rq_flags)) {
+		if (*statp == rpc_drop_reply ||
+		    test_bit(RQ_DROPME, &rqstp->rq_flags)) {
 			if (procp->pc_release)
 				procp->pc_release(rqstp, NULL, rqstp->rq_resp);
 			goto dropit;