[lttng-dev] [PATCH lttng-tools] Fix: do not repurpose iterator while it is being used

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Wed Dec 12 17:24:11 EST 2018


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.

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 9cc91cc4..9d82b831 100644
--- a/src/bin/lttng-sessiond/notification-thread-events.c
+++ b/src/bin/lttng-sessiond/notification-thread-events.c
@@ -1931,6 +1931,7 @@ int bind_trigger_to_matching_channels(const struct lttng_trigger *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;
@@ -1940,8 +1941,8 @@ int bind_trigger_to_matching_channels(const struct lttng_trigger *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



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