From: Chuck Lever <chuck.lever@oracle.com>
Date: Fri, 23 Jun 2017 17:17:24 -0400
Subject: svcrdma: Avoid Send Queue overflow
Patch-mainline: v4.13-rc1
Git-commit: 107c1d0a991abe632a051de697c5acc33c03fd96
References: bsc#1103992 FATE#326009

Sanity case: Catch the case where more Work Requests are being
posted to the Send Queue than there are Send Queue Entries.

This might happen if a client sends a chunk with more segments than
there are SQEs for the transport. The server can't send that reply,
so the transport will deadlock unless the client drops the RPC.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sunrpc/xprtrdma/svc_rdma_rw.c     |    5 +++++
 net/sunrpc/xprtrdma/svc_rdma_sendto.c |    2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

--- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
@@ -232,6 +232,9 @@ static int svc_rdma_post_chunk_ctxt(stru
 	struct ib_cqe *cqe;
 	int ret;
 
+	if (cc->cc_sqecount > rdma->sc_sq_depth)
+		return -EINVAL;
+
 	first_wr = NULL;
 	cqe = &cc->cc_cqe;
 	list_for_each(tmp, &cc->cc_rwctxts) {
@@ -425,6 +428,7 @@ static int svc_rdma_send_xdr_pagelist(st
  *
  * Returns a non-negative number of bytes the chunk consumed, or
  *	%-E2BIG if the payload was larger than the Write chunk,
+ *	%-EINVAL if client provided too many segments,
  *	%-ENOMEM if rdma_rw context pool was exhausted,
  *	%-ENOTCONN if posting failed (connection is lost),
  *	%-EIO if rdma_rw initialization failed (DMA mapping, etc).
@@ -465,6 +469,7 @@ out_err:
  *
  * Returns a non-negative number of bytes the chunk consumed, or
  *	%-E2BIG if the payload was larger than the Reply chunk,
+ *	%-EINVAL if client provided too many segments,
  *	%-ENOMEM if rdma_rw context pool was exhausted,
  *	%-ENOTCONN if posting failed (connection is lost),
  *	%-EIO if rdma_rw initialization failed (DMA mapping, etc).
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -684,7 +684,7 @@ int svc_rdma_sendto(struct svc_rqst *rqs
 	return 0;
 
  err2:
-	if (ret != -E2BIG)
+	if (ret != -E2BIG || ret != -EINVAL)
 		goto err1;
 
 	ret = svc_rdma_post_recv(rdma, GFP_KERNEL);