From a04c2a398dc9069297b416477ada3f8a3d675741 Mon Sep 17 00:00:00 2001 From: Baptiste Lepers Date: Sat, 1 May 2021 14:10:51 +1000 Subject: sunrpc: Fix misplaced barrier in call_decode [ Upstream commit f8f7e0fb22b2e75be55f2f0c13e229e75b0eac07 ] Fix a misplaced barrier in call_decode. The struct rpc_rqst is modified as follows by xprt_complete_rqst: req->rq_private_buf.len = copied; /* Ensure all writes are done before we update */ /* req->rq_reply_bytes_recvd */ smp_wmb(); req->rq_reply_bytes_recvd = copied; And currently read as follows by call_decode: smp_rmb(); // misplaced if (!req->rq_reply_bytes_recvd) goto out; req->rq_rcv_buf.len = req->rq_private_buf.len; This patch places the smp_rmb after the if to ensure that rq_reply_bytes_recvd and rq_private_buf.len are read in order. Fixes: 9ba828861c56a ("SUNRPC: Don't try to parse incomplete RPC messages") Signed-off-by: Baptiste Lepers Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- net/sunrpc/clnt.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'net/sunrpc/clnt.c') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index f1088ca39d44..b6039642df67 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -2505,12 +2505,6 @@ call_decode(struct rpc_task *task) task->tk_flags &= ~RPC_CALL_MAJORSEEN; } - /* - * Ensure that we see all writes made by xprt_complete_rqst() - * 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. @@ -2519,6 +2513,11 @@ call_decode(struct rpc_task *task) if (!req->rq_reply_bytes_recvd) goto out; + /* Ensure that we see all writes made by xprt_complete_rqst() + * before it changed req->rq_reply_bytes_recvd. + */ + smp_rmb(); + req->rq_rcv_buf.len = req->rq_private_buf.len; /* Check that the softirq receive buffer is valid */ -- cgit v1.2.3