On Thu, Feb 20, 2014 at 06:44:59PM +0100, Mateusz Guzik wrote:
> In use after free situations, it is possible for one thread to write to
> memory that has just been reallocated to a new user. This could open up
> potential security issues.
>
> diff --git a/include/linux/kref.h b/include/linux/kref.h
> index 484604d..c3f8a0a 100644
> --- a/include/linux/kref.h
> +++ b/include/linux/kref.h
> @@ -43,8 +43,10 @@ static inline void kref_get(struct kref *kref)
> /* If refcount was 0 before incrementing then we have a race
> * condition when this kref is freeing by some other thread right now.
> * In this case one should use kref_get_unless_zero()
> + *
> + * Terminate the current thread to stop potential security exploits.
> */
> - WARN_ON_ONCE(atomic_inc_return(&kref->refcount) < 2);
> + BUG_ON(atomic_inc_return(&kref->refcount) < 2);
This isn't "terminating the thread", this is "lock up the box".
Dave
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