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

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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: a949ae560a "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>
This commit is contained in:
Steven Rostedt (Red Hat) 2016-01-05 20:32:47 -05:00 committed by Steven Rostedt
parent f36d1be293
commit 049fb9bd41
2 changed files with 7 additions and 0 deletions
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1
include/linux/ftrace.h
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@ -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);

6
kernel/module.c
View File

@ -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);