linux-kernel - RE: [PATCH] PCI: endpoint: Fix NULL pointer dereference for ->get

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Date:   Mon, 6 Jul 2020 18:47:30 +0530
From:   "Sriram Dash" <sriram.dash@...sung.com>
To:     "'Lorenzo Pieralisi'" <lorenzo.pieralisi@....com>
Cc:     "'Kishon Vijay Abraham I'" <kishon@...com>,
        "'Shradha Todi'" <shradha.t@...sung.com>, <bhelgaas@...gle.com>,
        <pankaj.dubey@...sung.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] PCI: endpoint: Fix NULL pointer dereference for
 ->get_features()

> From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Sent: 06 July 2020 16:47
> Subject: Re: [PATCH] PCI: endpoint: Fix NULL pointer dereference for -
> >get_features()
> 
> On Thu, Apr 02, 2020 at 08:01:59PM +0530, Sriram Dash wrote:
> 
> [...]
> 
> > > So the patch itself is correct though the commit log has to be
> > > fixed. You should also check if all the endpoint controller drivers
> > > existing currently provides epc_features.
> >
> > At the moment, there is no issue for existing controller drivers as I
> > can see almost all drivers are providing epc_features. But, this is
> > not a mandatory feature and some controller drivers may not have
> > epc_features implemented, may be in the near future.  But because we
> > are dealing with the configfs, the application need not bother about
> > the driver details underneath.
> >
> > IMO, the code should be fixed regardless and should not cause panic in
> > any case.
> 
> What's this patch status please ?
>

Its not in the mainline tree as of now. However, we feel its important for
the drivers not using epc_features.
 
> Thanks,
> Lorenzo
> 
> > > Thanks
> > > Kishon
> > > >
> > > >
> > > >>  drivers/pci/endpoint/functions/pci-epf-test.c | 15
> > > >> +++++++++------
> > > >>  1 file changed, 9 insertions(+), 6 deletions(-)
> > > >>
> > > >> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> index c9121b1b9fa9..af4537a487bf 100644
> > > >> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > >> @@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf
*epf)
> > > >>  		return -EINVAL;
> > > >>
> > > >>  	epc_features = pci_epc_get_features(epc, epf->func_no);
> > > >> -	if (epc_features) {
> > > >> -		linkup_notifier = epc_features->linkup_notifier;
> > > >> -		msix_capable = epc_features->msix_capable;
> > > >> -		msi_capable = epc_features->msi_capable;
> > > >> -		test_reg_bar =
pci_epc_get_first_free_bar(epc_features);
> > > >> -		pci_epf_configure_bar(epf, epc_features);
> > > >> +	if (!epc_features) {
> > > >> +		dev_err(dev, "epc_features not implemented\n");
> > > >> +		return -ENOTSUPP;
> > > >>  	}
> > > >>
> > > >> +	linkup_notifier = epc_features->linkup_notifier;
> > > >> +	msix_capable = epc_features->msix_capable;
> > > >> +	msi_capable = epc_features->msi_capable;
> > > >> +	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> > > >> +	pci_epf_configure_bar(epf, epc_features);
> > > >> +
> > > >>  	epf_test->test_reg_bar = test_reg_bar;
> > > >>  	epf_test->epc_features = epc_features;
> > > >>
> > > >> --
> > > >> 2.17.1
> > > >
> > > >
> >