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PeiyangX Qiu reported that if a module fails to load between calling 

ftrace_module_init() and do_init_module() that the allocations made
 in ftrace_module_init() will not be freed, resulting in a memory leak.
 
 The solution is to call ftrace_release_mod() on the failing module in
 the fail path befor do_init_module() is called. This will remove any
 allocations made for that module, and nothing if ftrace_module_init()
 wasn't called yet for that module.
 
 Note, once do_init_module() is called, the MODULE_GOING notifiers are
 called for the failed module, which calls into the ftrace code to do the
 proper clean up (basically calling ftrace_release_mod()).
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Merge tag 'trace-v4.4-rc4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull ftrace fix from Steven Rostedt:
 "PeiyangX Qiu reported that if a module fails to load between calling
  ftrace_module_init() and do_init_module() that the allocations made in
  ftrace_module_init() will not be freed, resulting in a memory leak.

  The solution is to call ftrace_release_mod() on the failing module in
  the fail path befor do_init_module() is called.  This will remove any
  allocations made for that module, and nothing if ftrace_module_init()
  wasn't called yet for that module.

  Note, once do_init_module() is called, the MODULE_GOING notifiers are
  called for the failed module, which calls into the ftrace code to do
  the proper clean up (basically calling ftrace_release_mod())"

* tag 'trace-v4.4-rc4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/module: Call clean up function when module init fails early
This commit is contained in:
Linus Torvalds 2016-01-07 12:42:22 -08:00
parent b06f3a168c 049fb9bd41
commit 2626820d83
2 changed files with 7 additions and 0 deletions
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1
include/linux/ftrace.h
View File

@ -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);