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

On Mon, Mar 12, 2018 at 4:17 PM, Cong Wang [off-list ref] wrote:

On Sun, Mar 11, 2018 at 12:22 PM, Josh Elsasser [off-list ref] wrote:

quoted

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.