On Fri, Mar 02, 2018 at 08:44:26PM +0100, Andrey Konovalov wrote:
> +static DEFINE_PER_CPU(u32, prng_state);
> +
> +void khwasan_init(void)
> +{
> + int cpu;
> +
> + for_each_possible_cpu(cpu) {
> + per_cpu(prng_state, cpu) = get_random_u32();
> + }
> + WRITE_ONCE(khwasan_enabled, 1);
> +}
> +
> +static inline u8 khwasan_random_tag(void)
> +{
> + u32 state = this_cpu_read(prng_state);
> +
> + state = 1664525 * state + 1013904223;
> + this_cpu_write(prng_state, state);
> +
> + return (u8)state;
> +}
Have you considered preemption here? Is the assumption that it happens
sufficiently rarely that cross-contaminating the prng state isn't a
problem?
Thanks,
Mark.
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