Subject: Re: [Intel-wired-lan] [PATCH net] idpf: fix double free and use-after-free in aux device error paths

From: Greg Kroah-Hartman <[email-masked]>
Date: Tue, 14 Apr 2026 10:00:06 +0200

On Tue, Apr 14, 2026 at 08:54:55AM +0200, Paul Menzel wrote:
> Dear Greg,
> 
> 
> Thank you for the patch.
> 
> Am 11.04.26 um 12:12 schrieb Greg Kroah-Hartman:
> > When auxiliary_device_add() fails in idpf_plug_vport_aux_dev() or
> > idpf_plug_core_aux_dev(), the err_aux_dev_add label calls
> > auxiliary_device_uninit() and falls through to err_aux_dev_init.  The
> > uninit call will trigger put_device(), which invokes the release
> > callback (idpf_vport_adev_release / idpf_core_adev_release) that frees
> > iadev.  The fall-through then reads adev->id from the freed iadev for
> > ida_free() and double-frees iadev with kfree().
> > 
> > Free the IDA slot and clear the back-pointer before uninit, while adev
> > is still valid, then return immediately.
> > 
> > Commit 65637c3a1811 65637c3a1811 ("idpf: fix UAF in RDMA core aux dev
> 
> The commit hash is pasted twice.

Argh, when I cut/paste from my terminal that happened, my fault.

> > deinitialization") fixed the same use-after-free in the matching unplug
> > path in this file but missed both probe error paths.
> > 
> > Cc: Tony Nguyen <[email-masked]>
> > Cc: Przemek Kitszel <[email-masked]>
> > Cc: Andrew Lunn <[email-masked]>
> > Cc: "David S. Miller" <[email-masked]>
> > Cc: Eric Dumazet <[email-masked]>
> > Cc: Jakub Kicinski <[email-masked]>
> > Cc: Paolo Abeni <[email-masked]>
> > Cc: stable <[email-masked]>
> > Fixes: be91128c579c ("idpf: implement RDMA vport auxiliary dev create, init, and destroy")
> > Fixes: f4312e6bfa2a ("idpf: implement core RDMA auxiliary dev create, init, and destroy")
> > Assisted-by: gregkh_clanker_t1000
> > Signed-off-by: Greg Kroah-Hartman <[email-masked]>
> > ---
> > Note, these cleanup paths are messy, but I couldn't see a simpler way
> > without a lot more rework, so I choose the simple way :)
> > 
> >   drivers/net/ethernet/intel/idpf/idpf_idc.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/intel/idpf/idpf_idc.c b/drivers/net/ethernet/intel/idpf/idpf_idc.c
> > index 7e4f4ac92653..b7d6b08fc89e 100644
> > --- a/drivers/net/ethernet/intel/idpf/idpf_idc.c
> > +++ b/drivers/net/ethernet/intel/idpf/idpf_idc.c
> > @@ -90,7 +90,10 @@ static int idpf_plug_vport_aux_dev(struct iidc_rdma_core_dev_info *cdev_info,
> >   	return 0;
> >   err_aux_dev_add:
> > +	ida_free(&idpf_idc_ida, adev->id);
> > +	vdev_info->adev = NULL;
> >   	auxiliary_device_uninit(adev);
> > +	return ret;
> >   err_aux_dev_init:
> >   	ida_free(&idpf_idc_ida, adev->id);
> >   err_ida_alloc:
> > @@ -228,7 +231,10 @@ static int idpf_plug_core_aux_dev(struct iidc_rdma_core_dev_info *cdev_info)
> >   	return 0;
> >   err_aux_dev_add:
> > +	ida_free(&idpf_idc_ida, adev->id);
> > +	cdev_info->adev = NULL;
> >   	auxiliary_device_uninit(adev);
> > +	return ret;
> >   err_aux_dev_init:
> >   	ida_free(&idpf_idc_ida, adev->id);
> >   err_ida_alloc:
> 
> Reviewed-by: Paul Menzel <[email-masked]>
> 
> gemini/gemini-3.1-pro-preview has two comments [1]. Maybe the driver
> developers could judge their relevance.

These "pre-existing" reports are getting annoying.  While they are nice
to see for driver authors, it makes developers sending bug fixes in feel
like they are forced to do "more".  I think they are trying to tune this
to be a bit more sane...

thanks,

greg k-h