[PATCH AUTOSEL 5.2 21/63] SUNRPC: Don't try to parse incomplete RPC messages

Sasha Levin
2019-10-01T16:56:52Z

From: Trond Myklebust <trondmy@gmail.com>

[ Upstream commit 9ba828861c56a21d211d5d10f5643774b1ea330d ]

If the copy of the RPC reply into our buffers did not complete, and
we could end up with a truncated message. In that case, just resend
the call.

Fixes: a0584ee9aed80 ("SUNRPC: Use struct xdr_stream when decoding...")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/clnt.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 8f32f73614111..866b60313fb12 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2398,6 +2398,7 @@ call_decode(struct rpc_task *task)
struct rpc_clnt *clnt = task->tk_client;
struct rpc_rqst *req = task->tk_rqstp;
struct xdr_stream xdr;
+ int err;

dprint_status(task);

@@ -2420,6 +2421,15 @@ call_decode(struct rpc_task *task)
* before it changed req->rq_reply_bytes_recvd.
*/
smp_rmb();
+
+ /*
+ * Did we ever call xprt_complete_rqst()? If not, we should assume
+ * the message is incomplete.
+ */
+ err = -EAGAIN;
+ if (!req->rq_reply_bytes_recvd)
+ goto out;
+
req->rq_rcv_buf.len = req->rq_private_buf.len;

/* Check that the softirq receive buffer is valid */
@@ -2428,7 +2438,9 @@ call_decode(struct rpc_task *task)

xdr_init_decode(&xdr, &req->rq_rcv_buf,
req->rq_rcv_buf.head[0].iov_base, req);
- switch (rpc_decode_header(task, &xdr)) {
+ err = rpc_decode_header(task, &xdr);
+out:
+ switch (err) {
case 0:
task->tk_action = rpc_exit_task;
task->tk_status = rpcauth_unwrap_resp(task, &xdr);
--
2.20.1