Re: perf: fuzzer triggers NULL pointer derefreence in x86_schedule_events

[Peter Zijlstra]

On Wed, May 20, 2015 at 03:49:22PM +0200, Peter Zijlstra wrote:
> ---
>  kernel/events/core.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 1a3bf48..a4f93fb 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7391,13 +7391,16 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
>  		ctx = perf_event_ctx_lock_nested(event->group_leader,
>  						 SINGLE_DEPTH_NESTING);
>  		BUG_ON(!ctx);
> +		raw_spin_lock_irq(&ctx->lock);
>  	}
>  
>  	event->pmu = pmu;
>  	ret = pmu->event_init(event);
>  
> -	if (ctx)
> +	if (ctx) {
> +		raw_spin_unlock_irq(&ctx->lock);
>  		perf_event_ctx_unlock(event->group_leader, ctx);
> +	}
>  
>  	if (ret)
>  		module_put(pmu->module);

Except of course that ->event_init() likes to do an allocation :/

Needs to be fixed differently.
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