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SubjectRe: lockdep: Warning & NULL ptr deref
On Tue, Feb 28, 2012 at 4:20 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, 2012-02-28 at 16:19 +0200, Sasha Levin wrote:
>> On Tue, Feb 28, 2012 at 3:29 PM, Peter Zijlstra <peterz@infradead.org> wrote:
>> > On Tue, 2012-02-28 at 10:24 -0500, Sasha Levin wrote:
>> >>
>> >> I'll send some patches to prevent the NULL deref itself which happens
>> >> since a chunk of the code in lockdep.c assumed hlock_class() can't
>> >> return NULL.
>> >>
>> > There's tons of code actually assuming that..
>> >
>> >> This won't fix the actual problem though, I'm not sure exactly how a
>> >> held lock wouldn't have a class initialized to it.
>> >
>> > static inline struct lock_class *hlock_class(struct held_lock *hlock)
>> > {
>> >        if (!hlock->class_idx) {
>> >                /*
>> >                 * Someone passed in garbage, we give up.
>> >                 */
>> >                DEBUG_LOCKS_WARN_ON(1);
>> >                return NULL;
>> >        }
>> >        return lock_classes + hlock->class_idx - 1;
>> > }
>> >
>> > Typically that translates to severe memory corruption.
>>
>> I can also reproduce it easily by triggering sysrq once or twice after
>> trinity has stopped.
>
> What's trinity ?

Dave Jones' fuzzer tool. The git tree is located here:
http://codemonkey.org.uk/projects/trinity/trinity.git
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