linux-kernel - [PATCH 3.16 279/305] tracing: Fix memory leak of instance function hash filters

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Message-ID: <lsq.1549201508.695007448@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 3.16 279/305] tracing: Fix memory leak of instance
 function hash filters

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>

commit 2840f84f74035e5a535959d5f17269c69fa6edc5 upstream.

The following commands will cause a memory leak:

 # cd /sys/kernel/tracing
 # mkdir instances/foo
 # echo schedule > instance/foo/set_ftrace_filter
 # rmdir instances/foo

The reason is that the hashes that hold the filters to set_ftrace_filter and
set_ftrace_notrace are not freed if they contain any data on the instance
and the instance is removed.

Found by kmemleak detector.

Fixes: 591dffdade9f ("ftrace: Allow for function tracing instance to filter functions")
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 kernel/trace/ftrace.c | 1 +
 1 file changed, 1 insertion(+)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4127,6 +4127,7 @@ void ftrace_destroy_filter_files(struct
 	if (ops->flags & FTRACE_OPS_FL_ENABLED)
 		ftrace_shutdown(ops, 0);
 	ops->flags |= FTRACE_OPS_FL_DELETED;
+	ftrace_free_filter(ops);
 	mutex_unlock(&ftrace_lock);
 }