Re: [PATCH] net: xfrm: assign the per_cpu_ptr pointer before return

[Dongliang Mu]

On Wed, Aug 18, 2021 at 11:32 AM Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, Aug 18, 2021 at 11:25:53AM +0800, Dongliang Mu wrote:
> >
> > diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
> > index cb40ff0ff28d..01dbec70dfba 100644
> > --- a/net/xfrm/xfrm_ipcomp.c
> > +++ b/net/xfrm/xfrm_ipcomp.c
> > @@ -223,9 +223,9 @@ static void * __percpu *ipcomp_alloc_scratches(void)
> >               void *scratch;
> >
> >               scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
> > +             *per_cpu_ptr(scratches, i) = scratch;
> >               if (!scratch)
> >                       return NULL;
> > -             *per_cpu_ptr(scratches, i) = scratch;
>
> scratches comes from alloc_percpu so it should already be zeroed.

Correct.

:\ Then I have no idea how this crash occurs. This crash report does
not have any reproducer. It seems like a random crash, but I am not
sure.

If you have any patch for this crash, please let me know.

>
> Cheers,
> --
> Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt