From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 7 Sep 2015 14:36:09 +0000 (-0400)
Subject: Fix: unbalanced RCU read-side lock in enable event command
X-Git-Tag: v2.7.0-rc2~41
X-Git-Url: http://git.lttng.org/?a=commitdiff_plain;h=57dc4ef3fcea3490162dde4d09aa8c612b9ad4ad;p=lttng-tools.git

Fix: unbalanced RCU read-side lock in enable event command

The event validation fails, an unpaired RCU unlock is performed, thus
underflowing the RCU nesting counter.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 00e86a964..7b36ae252 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1521,13 +1521,13 @@ static int _cmd_enable_event(struct ltt_session *session,
 
 	DBG("Enable event command for event \'%s\'", event->name);
 
+	rcu_read_lock();
+
 	ret = validate_event_name(event->name);
 	if (ret) {
 		goto error;
 	}
 
-	rcu_read_lock();
-
 	switch (domain->type) {
 	case LTTNG_DOMAIN_KERNEL:
 	{