[PATCH 5.19 06/38] SUNRPC: Fix call completion races with call_decode()

Greg Kroah-Hartman
2022-09-21T15:47:57Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit 17814819ac9829a437e06fbb5c7056a1f4f893da ]

We need to make sure that the req->rq_private_buf is completely up to
date before we make req->rq_reply_bytes_recvd visible to the
call_decode() routine in order to avoid triggering the WARN_ON().

Reported-by: Benjamin Coddington <bcodding@redhat.com>
Fixes: 72691a269f0b ("SUNRPC: Don't reuse bvec on retransmission of the request")
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/xprt.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 53b024cea3b3..5ecafffe7ce5 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1179,11 +1179,8 @@ xprt_request_dequeue_receive_locked(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;

- if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
+ if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
xprt_request_rb_remove(req->rq_xprt, req);
- xdr_free_bvec(&req->rq_rcv_buf);
- req->rq_private_buf.bvec = NULL;
- }
}

/**
@@ -1221,6 +1218,8 @@ void xprt_complete_rqst(struct rpc_task *task, int copied)

xprt->stat.recvs++;

+ xdr_free_bvec(&req->rq_rcv_buf);
+ req->rq_private_buf.bvec = NULL;
req->rq_private_buf.len = copied;
/* Ensure all writes are done before we update */
/* req->rq_reply_bytes_recvd */
@@ -1453,6 +1452,7 @@ xprt_request_dequeue_xprt(struct rpc_task *task)
xprt_request_dequeue_transmit_locked(task);
xprt_request_dequeue_receive_locked(task);
spin_unlock(&xprt->queue_lock);
+ xdr_free_bvec(&req->rq_rcv_buf);
}
}

--
2.35.1