Re: [PATCH] skbuff: suppress clang object-size-mismatch error

[Tadeusz Struk]

On 11/11/21 07:52, Marco Elver wrote:
> > The other way to fix it would be to make the struct sk_buff_head
> > equal in size with struct sk_buff:
> >
> >    struct sk_buff_head {
> > -       /* These two members must be first. */
> > -       struct sk_buff  *next;
> > -       struct sk_buff  *prev;
> > +       union {
> > +               struct {
> > +                       /* These two members must be first. */
> > +                       struct sk_buff  *next;
> > +                       struct sk_buff  *prev;
> >
> > -       __u32           qlen;
> > -       spinlock_t      lock;
> > +                       __u32           qlen;
> > +                       spinlock_t      lock;
> > +               };
> > +               struct sk_buff  __prv;
> > +       };
> >    };
> >
> > but that's much more invasive, and I don't even have means to
> > quantify this in terms of final binary size and performance
> > impact. I think that would be a flat out no go.
> >
> >   From the other hand if you look at the __skb_queue functions
> > they don't do much and at all so there is no much room for
> > other issues really. I followed the suggestion in [1]:
> >
> > "if your function deliberately contains possible ..., you can
> >    use __attribute__((no_sanitize... "
> That general advice might not be compatible with what the kernel
> wants, especially since UBSAN_OBJECT_SIZE is normally disabled and I
> think known to cause these issues in the kernel.
>
> I'll defer to maintainers to decide what would be the preferred way of
> handling this.

Sure, I would also like to know if there is a better way of fixing this.
Thanks for your feedback.

--
Thanks,
Tadeusz