On Fri, Sep 29, 2017 at 5:26 PM, Vinicius Costa Gomes
[off-list ref] wrote:

From: Jesus Sanchez-Palencia <redacted>

In qdisc_alloc() the dev_queue pointer was used without any checks being
performed. If qdisc_create() gets a null dev_queue pointer, it just
passes it along to qdisc_alloc(), leading to a crash. That happens if a
root qdisc implements select_queue() and returns a null dev_queue
pointer for an "invalid handle", for example.

Does it make sense to let mqprio_select_queue() always return
non-NULL?

At least mq_select_queue() returns queue #0 as a fallback.