Re: [PATCH] platform/x86: ISST: fix use-after-free in tpmi_sst_dev_remove()

[srinivas pandruvada <srinivas.pandruvada@linux.intel.com>]

On Fri, 2024-05-17 at 07:31 -0700, srinivas pandruvada wrote:
> On Tue, 2024-05-14 at 02:26 -0700, Harshit Mogalapalli wrote:
> > In tpmi_sst_dev_remove(), tpmi_sst is dereferenced after being
> > freed.
> > Fix this by reordering the kfree() post the dereference.
> > 
> > Fixes: 9d1d36268f3d ("platform/x86: ISST: Support partitioned
> > systems")
> > Signed-off-by: Harshit Mogalapalli
> > <harshit.m.mogalapalli@oracle.com>
> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> 
I realized the line length is 127 chars in commit description.
Please fix that and run checkpatch.pl before posting again.

Thanks,
Srinivas

> > ---
> > This is found by smatch and only compile tested.
> > ---
> >  drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git
> > a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> > b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> > index 7bac7841ff0a..7fa360073f6e 100644
> > --- a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> > +++ b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> > @@ -1610,8 +1610,8 @@ void tpmi_sst_dev_remove(struct
> > auxiliary_device *auxdev)
> >         tpmi_sst->partition_mask_current &= ~BIT(plat_info-
> > > partition);
> >         /* Free the package instance when the all partitions are
> > removed */
> >         if (!tpmi_sst->partition_mask_current) {
> > -               kfree(tpmi_sst);
> >                 isst_common.sst_inst[tpmi_sst->package_id] = NULL;
> > +               kfree(tpmi_sst);
> >         }
> >         mutex_unlock(&isst_tpmi_dev_lock);
> >  }
>