rxrpc: Make /proc/net/rxrpc_calls safer

Make /proc/net/rxrpc_calls safer by stashing a copy of the peer pointer in
the rxrpc_call struct and checking in the show routine that the peer
pointer, the socket pointer and the local pointer obtained from the socket
pointer aren't NULL before we use them.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 19 insertions, 8 deletions

diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c
index 31b7f36a39cb..53872631a66d 100644
--- a/net/rxrpc/proc.c
+++ b/net/rxrpc/proc.c
@@ -46,7 +46,9 @@ static void rxrpc_call_seq_stop(struct seq_file *seq, void *v)
 
 static int rxrpc_call_seq_show(struct seq_file *seq, void *v)
 {
-	struct rxrpc_connection *conn;
+	struct rxrpc_local *local;
+	struct rxrpc_sock *rx;
+	struct rxrpc_peer *peer;
 	struct rxrpc_call *call;
 	char lbuff[4 + 4 + 4 + 4 + 5 + 1], rbuff[4 + 4 + 4 + 4 + 5 + 1];
 
@@ -60,15 +62,24 @@ static int rxrpc_call_seq_show(struct seq_file *seq, void *v)
 
 	call = list_entry(v, struct rxrpc_call, link);
 
-	sprintf(lbuff, "%pI4:%u",
-		&call->socket->local->srx.transport.sin.sin_addr,
-		ntohs(call->socket->local->srx.transport.sin.sin_port));
+	rx = READ_ONCE(call->socket);
+	if (rx) {
+		local = READ_ONCE(rx->local);
+		if (local)
+			sprintf(lbuff, "%pI4:%u",
+				&local->srx.transport.sin.sin_addr,
+				ntohs(local->srx.transport.sin.sin_port));
+		else
+			strcpy(lbuff, "no_local");
+	} else {
+		strcpy(lbuff, "no_socket");
+	}
 
-	conn = call->conn;
-	if (conn)
+	peer = call->peer;
+	if (peer)
 		sprintf(rbuff, "%pI4:%u",
-			&conn->params.peer->srx.transport.sin.sin_addr,
-			ntohs(conn->params.peer->srx.transport.sin.sin_port));
+			&peer->srx.transport.sin.sin_addr,
+			ntohs(peer->srx.transport.sin.sin_port));
 	else
 		strcpy(rbuff, "no_connection");