Patch "ftrace: Fix memleak when unregistering dynamic ops when tracing disabled" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ftrace: Fix memleak when unregistering dynamic ops when tracing disabled

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ftrace-fix-memleak-when-unregistering-dynamic-ops-when-tracing-disabled.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From edb096e00724f02db5f6ec7900f3bbd465c6c76f Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Date: Fri, 1 Sep 2017 12:18:28 -0400
Subject: ftrace: Fix memleak when unregistering dynamic ops when tracing disabled

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

commit edb096e00724f02db5f6ec7900f3bbd465c6c76f upstream.

If function tracing is disabled by the user via the function-trace option or
the proc sysctl file, and a ftrace_ops that was allocated on the heap is
unregistered, then the shutdown code exits out without doing the proper
clean up. This was found via kmemleak and running the ftrace selftests, as
one of the tests unregisters with function tracing disabled.

 # cat kmemleak
unreferenced object 0xffffffffa0020000 (size 4096):
  comm "swapper/0", pid 1, jiffies 4294668889 (age 569.209s)
  hex dump (first 32 bytes):
    55 ff 74 24 10 55 48 89 e5 ff 74 24 18 55 48 89  U.t$.UH...t$.UH.
    e5 48 81 ec a8 00 00 00 48 89 44 24 50 48 89 4c  .H......H.D$PH.L
  backtrace:
    [<ffffffff81d64665>] kmemleak_vmalloc+0x85/0xf0
    [<ffffffff81355631>] __vmalloc_node_range+0x281/0x3e0
    [<ffffffff8109697f>] module_alloc+0x4f/0x90
    [<ffffffff81091170>] arch_ftrace_update_trampoline+0x160/0x420
    [<ffffffff81249947>] ftrace_startup+0xe7/0x300
    [<ffffffff81249bd2>] register_ftrace_function+0x72/0x90
    [<ffffffff81263786>] trace_selftest_ops+0x204/0x397
    [<ffffffff82bb8971>] trace_selftest_startup_function+0x394/0x624
    [<ffffffff81263a75>] run_tracer_selftest+0x15c/0x1d7
    [<ffffffff82bb83f1>] init_trace_selftests+0x75/0x192
    [<ffffffff81002230>] do_one_initcall+0x90/0x1e2
    [<ffffffff82b7d620>] kernel_init_freeable+0x350/0x3fe
    [<ffffffff81d61ec3>] kernel_init+0x13/0x122
    [<ffffffff81d72c6a>] ret_from_fork+0x2a/0x40
    [<ffffffffffffffff>] 0xffffffffffffffff

Fixes: 12cce594fa ("ftrace/x86: Allow !CONFIG_PREEMPT dynamic ops to use allocated trampolines")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/ftrace.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2667,13 +2667,14 @@ static int ftrace_shutdown(struct ftrace
 
 	if (!command || !ftrace_enabled) {
 		/*
-		 * If these are control ops, they still need their
-		 * per_cpu field freed. Since, function tracing is
+		 * If these are dynamic or control ops, they still
+		 * need their data freed. Since, function tracing is
 		 * not currently active, we can just free them
 		 * without synchronizing all CPUs.
 		 */
-		if (ops->flags & FTRACE_OPS_FL_CONTROL)
-			control_ops_free(ops);
+		if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_CONTROL))
+			goto free_ops;
+
 		return 0;
 	}
 
@@ -2728,6 +2729,7 @@ static int ftrace_shutdown(struct ftrace
 	if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_CONTROL)) {
 		schedule_on_each_cpu(ftrace_sync);
 
+ free_ops:
 		arch_ftrace_trampoline_free(ops);
 
 		if (ops->flags & FTRACE_OPS_FL_CONTROL)


Patches currently in stable-queue which might be from rostedt@goodmis.org are

queue-4.4/ftrace-fix-memleak-when-unregistering-dynamic-ops-when-tracing-disabled.patch
queue-4.4/tracing-apply-trace_clock-changes-to-instance-max-buffer.patch
queue-4.4/ftrace-fix-selftest-goto-location-on-error.patch