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SubjectRe: [syzbot] WARNING in u32_change
To be clear, that splat didnt happen for me.
Is there something else syzbot does to activate it?

cheers,
jamal

On Sun, Sep 25, 2022 at 1:08 PM Jamal Hadi Salim <jhs@mojatatu.com> wrote:
>
> Yes, after testing i realize there is nothing wrong here.
> What warning was i supposed to see from running the reproducer?
>
> We will still add the test will multiple keys later
>
> cheers,
> jamal
>
> On Sun, Sep 25, 2022 at 12:29 PM Eric Dumazet <edumazet@google.com> wrote:
> >
> > On Sun, Sep 25, 2022 at 9:14 AM Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> > >
> > > On Sun, Sep 25, 2022 at 11:38 AM Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> > > >
> > > > Is there a way to tell the boat "looking into it?"
> > >
> > >
> > > I guess I have to swim across to it to get the message;->
> > >
> > > I couldnt see the warning message but it is obvious by inspection that
> > > the memcpy is broken. We should add more test coverage.
> > > This should fix it. Will send a formal patch later:
> > >
> > > diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
> > > index 4d27300c2..591cbbf27 100644
> > > --- a/net/sched/cls_u32.c
> > > +++ b/net/sched/cls_u32.c
> > > @@ -1019,7 +1019,7 @@ static int u32_change(struct net *net, struct
> > > sk_buff *in_skb,
> > > }
> > >
> > > s = nla_data(tb[TCA_U32_SEL]);
> > > - sel_size = struct_size(s, keys, s->nkeys);
> > > + sel_size = struct_size(s, keys, s->nkeys) + sizeof(n->sel);
> > > if (nla_len(tb[TCA_U32_SEL]) < sel_size) {
> > > err = -EINVAL;
> > > goto erridr;
> >
> > This patch is not needed, please look at struct_size() definition.
> >
> > Here, we might switch to unsafe_memcpy() instead of memcpy()

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