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

[Harshit Mogalapalli]

On 17/05/24 20:03, srinivas pandruvada wrote:
> 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@xxxxxxxxxx>
> > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
> I realized the line length is 127 chars in commit description.
> Please fix that and run checkpatch.pl before posting again.

Thanks for the ACK.

Sorry I usually run checkpatch.pl, but somehow missed noticing the 
error. Will send it with the commit message fixup.

Thanks,
Harshit
> 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);
> > >   }