Re: [Intel-wired-lan] [PATCH v2] dpf: fix UAF and double free in idpf_plug_vport_aux_dev() error path

Guangshuo Li
2026-04-15T01:48:10Z

Hi Jacob,

Thanks for reviewing.

On Wed, 15 Apr 2026 at 05:03, Jacob Keller <jacob.e.keller@intel.com> wrote:
>
>
> This doesn't look right. The commit message analysis seems to match this
> fix from Greg KH:
>
> https://lore.kernel.org/intel-wired-lan/2026041432-tapestry-condition-22ff@gregkh/
>
> But the changes do not make any sense to me. It looks like a poorly done
> AI-generated "fix" which is not correct. Greg's version does look like
> it properly resolves this.
>
> > v2:
> > - note that the issue was identified by my static analysis tool
> > - and confirmed by manual review
> >
>
> What even is this change log?? I see that version was sent and everyone
> else was sane enough to just silently reject or ignore the v1...
>
> > drivers/net/ethernet/intel/idpf/idpf_idc.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/intel/idpf/idpf_idc.c b/drivers/net/ethernet/intel/idpf/idpf_idc.c
> > index 6dad0593f7f2..2a18907643fc 100644
> > --- a/drivers/net/ethernet/intel/idpf/idpf_idc.c
> > +++ b/drivers/net/ethernet/intel/idpf/idpf_idc.c
> > @@ -59,6 +59,7 @@ static int idpf_plug_vport_aux_dev(struct iidc_rdma_core_dev_info *cdev_info,
> > char name[IDPF_IDC_MAX_ADEV_NAME_LEN];
> > struct auxiliary_device *adev;
> > int ret;
> > + int adev_id;
> >
>
> You create a local variable here...
>
> > iadev = kzalloc(sizeof(*iadev), GFP_KERNEL);
> > if (!iadev)
> > @@ -74,11 +75,14 @@ static int idpf_plug_vport_aux_dev(struct iidc_rdma_core_dev_info *cdev_info,
> > goto err_ida_alloc;
> > }
> > adev->id = ret;
> > + adev->id = adev_id;
>
> adev_is is never initialized, so you assign a random garbage
> uninitialized value. This is obviously wrong and will lead to worse
> errors than the failed cleanup.
>
> I'm rejecting this patch in favor of the clearly appropriate fix from Greg.
>
> > adev->dev.release = idpf_vport_adev_release;
> > adev->dev.parent = &cdev_info->pdev->dev;
> > sprintf(name, "%04x.rdma.vdev", cdev_info->pdev->vendor);
> > adev->name = name;
> >
> > + /* iadev is owned by the auxiliary device */
> > + iadev = NULL;> ret = auxiliary_device_init(adev);
> > if (ret)
> > goto err_aux_dev_init;
> > @@ -92,7 +96,7 @@ static int idpf_plug_vport_aux_dev(struct iidc_rdma_core_dev_info *cdev_info,
> > err_aux_dev_add:
> > auxiliary_device_uninit(adev);
> > err_aux_dev_init:
> > - ida_free(&idpf_idc_ida, adev->id);
> > + ida_free(&idpf_idc_ida, adev_id);
> > err_ida_alloc:
> > vdev_info->adev = NULL;
> > kfree(iadev);
>

You are right that the v2 patch as sent is incomplete. That was my
mistake when preparing/sending v2: it accidentally dropped the adev_id
= ret; assignment, which made that version incorrect.

For reference, the original v1 patch is here:

https://lkml.org/lkml/2026/3/21/421

In v1, adev_id was assigned from ret before use, so I believe that
particular uninitialized-variable issue was introduced in the v2
posting.

Sorry for the confusion caused by the broken v2 posting.

Thanks,
Guangshuo