Re: [net RFC v1 1/1] page_pool: fix NULL dereference crash

[Jesper Dangaard Brouer]

On 22/01/2022 03.40, Colin Foster wrote:
> On Fri, Jan 21, 2022 at 05:13:28PM -0800, Alexei Starovoitov wrote:
> > On Fri, Jan 21, 2022 at 4:57 PM Colin Foster
> > <colin.foster@xxxxxxxxxxxxxxxx> wrote:
> > > Check for the existence of page pool params before dereferencing. This can
> > > cause crashes in certain conditions.
> >
> > In what conditions?
> > Out of tree driver?
> >
> > > Fixes: 35b2e549894b ("page_pool: Add callback to init pages when they are
> > > allocated")
> > >
> > > Signed-off-by: Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>
> > > ---
> > >   net/core/page_pool.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> > > index bd62c01a2ec3..641f849c95e7 100644
> > > --- a/net/core/page_pool.c
> > > +++ b/net/core/page_pool.c
> > > @@ -213,7 +213,7 @@ static void page_pool_set_pp_info(struct page_pool *pool,
> > >   {
> > >          page->pp = pool;
> > >          page->pp_magic |= PP_SIGNATURE;
> > > -       if (pool->p.init_callback)
> > > +       if (pool->p && pool->p.init_callback)
>
> And my apologies - this should be if (pool... not if (pool->p. kernelbot
> will be sure to tell me of this blunder soon

Can you confirm if your crash is fixed by this change?


> > >                  pool->p.init_callback(page, pool->p.init_arg);
> > >   }