Re: [PATCH net v2] net/sched: sch_netem: prevent packet length underflow with negative overhead

[Bui Viet Dung]

Hi,

Thanks for the detailed review. Both points are valid and critical:

1. mul_u64_u64_div_u64() on x86-64 uses 'divq' without overflow handling,
   which raises a #DE divide exception when (len * NSEC_PER_SEC) / rate
   overflows u64.
2. Returning S64_MAX can overflow the subsequent 'now + delay' addition in
   netem_enqueue().

I will retract v2 and prepare a proper v3.

pw-bot: cr