Re: [PATCH 1/1] net: check dev->reg_state before deref of napi netdev_ops

[Josh Elsasser]

On Mon, Mar 12, 2018 at 4:17 PM, Cong Wang <xiyou.wangcong@xxxxxxxxx> wrote:
> On Sun, Mar 11, 2018 at 12:22 PM, Josh Elsasser <jelsasser@xxxxxxxxxxx> wrote:
>> init_dummy_netdev() leaves its netdev_ops pointer zeroed. This leads
>> to a NULL pointer dereference when sk_busy_loop fires against an iwlwifi
>> wireless adapter and checks napi->dev->netdev_ops->ndo_busy_poll.
>>
>> Avoid this by ensuring that napi->dev is not a dummy device before
>> dereferencing napi dev's netdev_ops, preventing the following panic:
>
> Hmm, how about just checking ->netdev_ops? Checking reg_state looks
> odd, although works.

Fair point. I was trying to differentiate between an unexpected
NULL pointer and a dummy netdev, but I guess it was clever
at the expense of readability.

I'll push up a v2 that just does the obvious.