Commit 049fb9bd authored Jan 05, 2016 by Steven Rostedt (Red Hat) Committed by Steven Rostedt Jan 07, 2016

ftrace/module: Call clean up function when module init fails early

If the module init code fails after calling ftrace_module_init() and before
calling do_init_module(), we can suffer from a memory leak. This is because
ftrace_module_init() allocates pages to store the locations that ftrace
hooks are placed in the module text. If do_init_module() fails, it still
calls the MODULE_GOING notifiers which will tell ftrace to do a clean up of
the pages it allocated for the module. But if load_module() fails before
then, the pages allocated by ftrace_module_init() will never be freed.

Call ftrace_release_mod() on the module if load_module() fails before
getting to do_init_module().

Link: http://lkml.kernel.org/r/567CEA31.1070507@intel.com

Reported-by: "Qiu, PeiyangX" <peiyangx.qiu@intel.com>
Fixes: a949ae56 "ftrace/module: Hardcode ftrace_module_init() call into load_module()"
Cc: stable@vger.kernel.org # v2.6.38+
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent f36d1be2

include/linux/ftrace.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -586,6 +586,7 @@ extern int ftrace_arch_read_dyn_info(char *buf, int size);

		extern int skip_trace(unsigned long ip);
		extern void ftrace_module_init(struct module *mod);
		extern void ftrace_release_mod(struct module *mod);

		extern void ftrace_disable_daemon(void);
		extern void ftrace_enable_daemon(void);

kernel/module.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -3571,6 +3571,12 @@ static int load_module(struct load_info info, const char __user uargs,
		synchronize_sched();
		mutex_unlock(&module_mutex);
		free_module:
		/*
		* Ftrace needs to clean up what it initialized.
		* This does nothing if ftrace_module_init() wasn't called,
		* but it must be called outside of module_mutex.
		*/
		ftrace_release_mod(mod);
		/* Free lock-classes; relies on the preceding sync_rcu() */
		lockdep_free_key_range(mod->module_core, mod->core_size);

Admin message