[Intel-wired-lan] [PATCH v2] idpf: nullify pointers after they are freed

[Salin, Samuel]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf Of Li Li
> via Intel-wired-lan
> Sent: Friday, January 23, 2026 12:01 AM
> To: Loktionov, Aleksandr <aleksandr.loktionov at intel.com>
> Cc: Nguyen, Anthony L <anthony.l.nguyen at intel.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel at intel.com>; David S. Miller <davem at davemloft.net>;
> Jakub Kicinski <kuba at kernel.org>; Eric Dumazet <edumazet at google.com>;
> intel-wired-lan at lists.osuosl.org; netdev at vger.kernel.org; linux-
> kernel at vger.kernel.org; David Decotigny <decot at google.com>; Singhai, Anjali
> <anjali.singhai at intel.com>; Samudrala, Sridhar
> <sridhar.samudrala at intel.com>; Brian Vazquez <brianvv at google.com>;
> Tantilov, Emil S <emil.s.tantilov at intel.com>
> Subject: Re: [Intel-wired-lan] [PATCH v2] idpf: nullify pointers after they are
> freed
> 
> On Thu, Jan 22, 2026 at 11:15 PM Loktionov, Aleksandr
> <aleksandr.loktionov at intel.com> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf
> > > Of Li Li via Intel-wired-lan
> > > Sent: Friday, January 23, 2026 7:58 AM
> > > To: Nguyen, Anthony L <anthony.l.nguyen at intel.com>; Kitszel,
> > > Przemyslaw <przemyslaw.kitszel at intel.com>; David S. Miller
> > > <davem at davemloft.net>; Jakub Kicinski <kuba at kernel.org>; Eric
> > > Dumazet <edumazet at google.com>; intel-wired-lan at lists.osuosl.org
> > > Cc: netdev at vger.kernel.org; linux-kernel at vger.kernel.org; David
> > > Decotigny <decot at google.com>; Singhai, Anjali
> > > <anjali.singhai at intel.com>; Samudrala, Sridhar
> > > <sridhar.samudrala at intel.com>; Brian Vazquez <brianvv at google.com>;
> > > Li Li <boolli at google.com>; Tantilov, Emil S
> > > <emil.s.tantilov at intel.com>
> > > Subject: [Intel-wired-lan] [PATCH v2] idpf: nullify pointers after
> > > they are freed
> > >
> > > rss_data->rss_key needs to be nullified after it is freed.
> > > Checks like "if (!rss_data->rss_key)" in the code could fail if it
> > > is not nullified.
> > >
> > > Tested: built and booted the kernel.
> > >
> > Good day ,Li Li
> >
> > Can you re-spin v3 and mention the reproduction steps (exact bash
> commands)?
> > The CALL trace from dmesg also is needed for users/admins to find the fix.
> 
> Thank you for the review. This patch isn't to fix any kernel panics we
> encountered. It is just to address a discrepancy I observed between the
> Google idpf and the upstream idpf as I was preparing for another patch about
> to be sent out. So far we haven't seen this particular dangling pointer cause
> any issues yet, but it's still a good practice to set it to NULL because there are
> other places guarded by this pointer being NULL, and it'd be great to avoid any
> race conditions.
> 
> >
> > Otherwise, fine
> > Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov at intel.com>
> >
> > > Fixes: 83f38f210b85 ("idpf: Fix RSS LUT NULL pointer crash on early
> > > ethtool operations")
> > > Signed-off-by: Li Li <boolli at google.com>
> > > ---
> > > Changes in v2:
> > >  - Remove the line to nullify vport->q_vector_idxs as it is not
> > >    necessary.
> > >
> > >  drivers/net/ethernet/intel/idpf/idpf_lib.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > > b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > > index 131a8121839bd..f63ab58428d2e 100644
> > > --- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > > +++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > > @@ -1308,6 +1308,7 @@ static struct idpf_vport
> > > *idpf_vport_alloc(struct idpf_adapter *adapter,
> > >
> > >  free_rss_key:
> > >       kfree(rss_data->rss_key);
> > > +     rss_data->rss_key = NULL;
> > >  free_vector_idxs:
> > >       kfree(vport->q_vector_idxs);
> > >  free_vport:
> > > --
> > > 2.52.0.457.g6b5491de43-goog
> >

Tested-by: Samuel Salin <Samuel.salin at intel.com>