On Thu, Dec 06, 2018 at 05:11:40PM -0800, Bart Van Assche wrote: > The next patch in this series uses the class name in code that > detects calls to lock_acquire() while a class key is being freed. Hence > retain the class name for lock classes that are being freed.
>From readin the discussion with v2; you meant to say: 'uses the class name pointer', right? You're not actually ever going to dereference it, since that would be a UaF. > > Cc: Peter Zijlstra <pet...@infradead.org> > Cc: Waiman Long <long...@redhat.com> > Cc: Johannes Berg <johan...@sipsolutions.net> > Signed-off-by: Bart Van Assche <bvanass...@acm.org> > --- > kernel/locking/lockdep.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > index ecd92969674c..92bdb187987f 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -4147,10 +4147,8 @@ static void zap_class(struct lock_class *class) > * Unhash the class and remove it from the all_lock_classes list: > */ > hlist_del_rcu(&class->hash_entry); > + class->hash_entry.pprev = NULL; > list_del(&class->lock_entry); > - > - RCU_INIT_POINTER(class->key, NULL); > - RCU_INIT_POINTER(class->name, NULL); > } > > static inline int within(const void *addr, void *start, unsigned long size) > -- > 2.20.0.rc2.403.gdbc3b29805-goog >
