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: [PATCH] ftrace: Fix memleak when unregistering dynamic ops when
tracing disabled
Git-commit: edb096e00724f02db5f6ec7900f3bbd465c6c76f
Patch-mainline: v4.14-rc1
References: bsc#1117174
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
Cc: stable@vger.kernel.org
Fixes: 12cce594fa ("ftrace/x86: Allow !CONFIG_PREEMPT dynamic ops to use allocated trampolines")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Petr Mladek <pmladek@suse.com>
---
kernel/trace/ftrace.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 165b149ccb1a..6abfafd7f173 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -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)
--
2.13.7