From: Baptiste Lepers baptiste.lepers@gmail.com
[ 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 baptiste.lepers@gmail.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sunrpc/clnt.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
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 */