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From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH 2/3] trace-cmd: Fix double free error when triggers are configured on multiple events
Date: Wed, 25 Mar 2020 16:08:28 +0200
Message-ID: <20200325140829.184651-3-tz.stoyanov@gmail.com> (raw)
In-Reply-To: <20200325140829.184651-1-tz.stoyanov@gmail.com>

When using trace-cmd "-e sched:* -R ..." command to set triggers to the all events
of given subsystem, trace-cmd fails with a double free error.
The problem is in create_event() function, where the config is expanded to the all
events. The same "event->trigger" pointer is copied to all events. Later, when the
trigger is applied, the update_event() frees this pointer multiple times.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 tracecmd/trace-record.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index ec3bcae9..7dbf599a 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -2702,7 +2702,8 @@ create_event(struct buffer_instance *instance, char *path, struct event_list *ol
 	else
 		free(p);
 
-	if (event->trigger) {
+	if (old_event->trigger) {
+		event->trigger = strdup(old_event->trigger);
 		ret = asprintf(&p, "%s/trigger", path_dirname);
 		if (ret < 0)
 			die("Failed to allocate trigger path for %s", path);
@@ -2883,6 +2884,7 @@ static void expand_event_instance(struct buffer_instance *instance)
 		event = compressed_list;
 		compressed_list = event->next;
 		expand_event(instance, event);
+		free(event->trigger);
 		free(event);
 	}
 }
-- 
2.25.1


  parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 14:08 [PATCH 0/3] Fix applying triggers to " Tzvetomir Stoyanov (VMware)
2020-03-25 14:08 ` [PATCH 1/3] trace-cmd: Fix check for trigger file in create_event() Tzvetomir Stoyanov (VMware)
2020-03-25 14:08 ` Tzvetomir Stoyanov (VMware) [this message]
2020-03-25 14:08 ` [PATCH 3/3] trace-cmd: Fix setting triggers to all events from given system Tzvetomir Stoyanov (VMware)

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