tracing: A couple of memory leaks found and fixed

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next

Head SHA1: edb096e00724f02db5f6ec7900f3bbd465c6c76f

Steven Rostedt (VMware) (2):
ftrace: Fix selftest goto location on error
ftrace: Fix memleak when unregistering dynamic ops when tracing disabled

----

 kernel/trace/ftrace.c         | 10 ++++++----
 kernel/trace/trace_selftest.c |  2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)

From: "Steven Rostedt (VMware)" <[email protected]>

In the second iteration of trace_selftest_ops(), the error goto label is wrong in the case where trace_selftest_test_global_cnt is off. In the case of error, it leaks the dynamic ops that was allocated.

---
 kernel/trace/trace_selftest.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index cb917cebae29..b17ec642793b 100644
@@ -273,7 +273,7 @@ static int trace_selftest_ops(struct trace_array *tr, int cnt)
 		goto out_free;
 	if (cnt > 1) {
 		if (trace_selftest_test_global_cnt == 0)
-			goto out;
+			goto out_free;
 	}
 	if (trace_selftest_test_dyn_cnt == 0)
 		goto out_free;

2.13.2

From: "Steven Rostedt (VMware)" <[email protected]>

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

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

index 165b149ccb1a..6abfafd7f173 100644
@@ -2828,13 +2828,14 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
 
 	if (!command || !ftrace_enabled) {
 		/*
-		 * If these are per_cpu ops, they still need their
-		 * per_cpu field freed. Since, function tracing is
+		 * If these are dynamic or per_cpu 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_PER_CPU)
-			per_cpu_ops_free(ops);
+		if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_PER_CPU))
+			goto free_ops;
+
 		return 0;
 	}
 

@@ -2900,6 +2901,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
 		if (IS_ENABLED(CONFIG_PREEMPT))
 			synchronize_rcu_tasks();
 
+ free_ops:
 		arch_ftrace_trampoline_free(ops);
 
 		if (ops->flags & FTRACE_OPS_FL_PER_CPU)

2.13.2