[PATCH 4.19 13/22] rxrpc: Call state should be read with READ_ONCE() under some circumstances

[Greg Kroah-Hartman]

From: Baptiste Lepers <baptiste.lepers@xxxxxxxxx>

[ Upstream commit a95d25dd7b94a5ba18246da09b4218f132fed60e ]

The call state may be changed at any time by the data-ready routine in
response to received packets, so if the call state is to be read and acted
upon several times in a function, READ_ONCE() must be used unless the call
state lock is held.

As it happens, we used READ_ONCE() to read the state a few lines above the
unmarked read in rxrpc_input_data(), so use that value rather than
re-reading it.

Fixes: a158bdd3247b ("rxrpc: Fix call timeouts")
Signed-off-by: Baptiste Lepers <baptiste.lepers@xxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Link: https://lore.kernel.org/r/161046715522.2450566.488819910256264150.stgit@xxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/rxrpc/input.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -446,7 +446,7 @@ static void rxrpc_input_data(struct rxrp
 	if (state >= RXRPC_CALL_COMPLETE)
 		return;
 
-	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
+	if (state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 		unsigned long timo = READ_ONCE(call->next_req_timo);
 		unsigned long now, expect_req_by;