From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Wed, 15 Jun 2016 21:18:03 +0000 (-0400)
Subject: Fix: sessiond ht_match_event() check if filter is NULL
X-Git-Tag: v2.7.4~3
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=65555e50c8953ae42c63a29374266aac6d2dabea;p=lttng-tools.git

Fix: sessiond ht_match_event() check if filter is NULL

It looks like an agent event's filter expression is NULL when
it's created with -a, for example:

    lttng enable-event -j -a

Since there's no check for this in ht_match_event(), strlen()
makes the session daemon segfault with this scenario:

    lttng create
    lttng enable-event -j -a
    lttng disable-event -j -a

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/agent.c b/src/bin/lttng-sessiond/agent.c
index 27e7d029c..988d2c4ab 100644
--- a/src/bin/lttng-sessiond/agent.c
+++ b/src/bin/lttng-sessiond/agent.c
@@ -90,11 +90,18 @@ static int ht_match_event(struct cds_lfht_node *node,
 	}
 
 	/* Filter expression */
-	if (strncmp(event->filter_expression, key->filter_expression,
-			strlen(event->filter_expression)) != 0) {
+	if (!!event->filter_expression ^ !!key->filter_expression) {
+		/* One has a filter expression, the other does not */
 		goto no_match;
 	}
 
+	if (event->filter_expression) {
+		if (strncmp(event->filter_expression, key->filter_expression,
+				strlen(event->filter_expression)) != 0) {
+			goto no_match;
+		}
+	}
+
 	return 1;
 
 no_match: