GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-19 13:11:14 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

lockdep: Fix the module unload key range freeing logic

Browse source 
Module unload calls lockdep_free_key_range(), which removes entries
from the data structures. Most of the lockdep code OTOH assumes the
data structures are append only; in specific see the comments in
add_lock_to_list() and look_up_lock_class().

Clearly this has only worked by accident; make it work proper. The
actual scenario to make it go boom would involve the memory freed by
the module unlock being re-allocated and re-used for a lock inside of
a rcu-sched grace period. This is a very unlikely scenario, still
better plug the hole.

Use RCU list iteration in all places and ammend the comments.

Change lockdep_free_key_range() to issue a sync_sched() between
removal from the lists and returning -- which results in the memory
being freed. Further ensure the callers are placed correctly and
comment the requirements.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Tsyvarev <tsyvarev@ispras.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2015-02-26 16:23:11 +01:00 • committed by Ingo Molnar
parent bc465aa9d0
commit 35a9393c95
2 changed files with 59 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

8
kernel/module.c
View file

@ -1865,7 +1865,7 @@ static void free_module(struct module *mod)
kfree(mod->args);
percpu_modfree(mod);
/* Free lock-classes: */
/* Free lock-classes; relies on the preceding sync_rcu(). */
lockdep_free_key_range(mod->module_core, mod->core_size);
/* Finally, free the core (containing the module structure) */
@ -3349,9 +3349,6 @@ static int load_module(struct load_info *info, const char __user *uargs,
module_bug_cleanup(mod);
mutex_unlock(&module_mutex);
/* Free lock-classes: */
lockdep_free_key_range(mod->module_core, mod->core_size);
/* we can't deallocate the module until we clear memory protection */
unset_module_init_ro_nx(mod);
unset_module_core_ro_nx(mod);
@ -3375,6 +3372,9 @@ static int load_module(struct load_info *info, const char __user *uargs,
synchronize_rcu();
mutex_unlock(&module_mutex);
free_module:
/* Free lock-classes; relies on the preceding sync_rcu() */
lockdep_free_key_range(mod->module_core, mod->core_size);
module_deallocate(mod, info);
free_copy:
free_copy(info);