[lttng-dev] [PATCH lttng-tools 2.10] Fix: do not repurpose iterator while it is being used (register trigger, 2.10)

[Mathieu Desnoyers]

The hash table iteration uses an iterator that needs to stay valid for
the next loop. Using that same iterator variable in a nested lookup in a
different hash table leads to segmentation fault.

This is a 2.10-specific instance of the issue affecting
bind_trigger_to_matching_channels() which was found in the
master and 2.11 branches. This one affects
handle_notification_thread_command_register_trigger().

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
 src/bin/lttng-sessiond/notification-thread-events.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/bin/lttng-sessiond/notification-thread-events.c b/src/bin/lttng-sessiond/notification-thread-events.c
index 6777fd6d..f54141e7 100644
--- a/src/bin/lttng-sessiond/notification-thread-events.c
+++ b/src/bin/lttng-sessiond/notification-thread-events.c
@@ -1119,6 +1119,7 @@ int handle_notification_thread_command_register_trigger(
 			channels_ht_node) {
 		struct lttng_trigger_list_element *trigger_list_element;
 		struct lttng_channel_trigger_list *trigger_list;
+		struct cds_lfht_iter lookup_iter;
 
 		if (!trigger_applies_to_channel(trigger, channel)) {
 			continue;
@@ -1128,8 +1129,8 @@ int handle_notification_thread_command_register_trigger(
 				hash_channel_key(&channel->key),
 				match_channel_trigger_list,
 				&channel->key,
-				&iter);
-		node = cds_lfht_iter_get_node(&iter);
+				&lookup_iter);
+		node = cds_lfht_iter_get_node(&lookup_iter);
 		assert(node);
 		trigger_list = caa_container_of(node,
 				struct lttng_channel_trigger_list,
-- 
2.11.0