linux-kernel - RE: [PATCH v2] PCI: endpoint: Fix NULL pointer dereference for ->get

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Message-ID: <096301d6d9b8$b440be00$1cc23a00$@samsung.com>
Date:   Thu, 24 Dec 2020 11:20:30 +0530
From:   "Shradha Todi" <shradha.t@...sung.com>
To:     "'Bjorn Helgaas'" <helgaas@...nel.org>
Cc:     <linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <kishon@...com>, <lorenzo.pieralisi@....com>,
        <bhelgaas@...gle.com>, <pankaj.dubey@...sung.com>,
        "'Sriram Dash'" <sriram.dash@...sung.com>
Subject: RE: [PATCH v2] PCI: endpoint: Fix NULL pointer dereference for
 ->get_features()

> From: Bjorn Helgaas <helgaas@...nel.org>
> Subject: Re: [PATCH v2] PCI: endpoint: Fix NULL pointer dereference for -
> >get_features()
> 
> On Fri, Dec 18, 2020 at 09:15:16PM +0530, Shradha Todi wrote:
> > get_features ops of pci_epc_ops may return NULL, causing NULL pointer
> > dereference in pci_epf_test_bind function. Let us add a check for
> > pci_epc_feature pointer in pci_epf_test_bind before we access it to
> > avoid any such NULL pointer dereference and return -ENOTSUPP in case
> > pci_epc_feature is not found.
> 
> Can you add a Fixes: tag to identify where this broke to help people
decide
> where to backport the fix?
> 

Thanks for the review. Sure we will add the Fixes tag and respin this patch.

> > Reviewed-by: Pankaj Dubey <pankaj.dubey@...sung.com>
> > Signed-off-by: Sriram Dash <sriram.dash@...sung.com>
> > Signed-off-by: Shradha Todi <shradha.t@...sung.com>
> > ---
> > v2:
> >  rebase on v1
> >  v1:
> > https://protect2.fireeye.com/v1/url?k=6193fa90-3e08c3dd-619271df-0cc47
> > aa8f5ba-a79111ee2c1d1660&q=1&e=a9ee1ef7-2713-4099-8d06-
> 738532d78b26&u=
> > https%3A%2F%2Flore.kernel.org%2Fpatchwork%2Fpatch%2F1208269%2F
> >
> >  drivers/pci/endpoint/functions/pci-epf-test.c | 13 ++++++++-----
> >  1 file changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c
> > b/drivers/pci/endpoint/functions/pci-epf-test.c
> > index 66723d5..f1842e6 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > @@ -835,13 +835,16 @@ 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;
> > -		core_init_notifier = epc_features->core_init_notifier;
> > -		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
> > -		pci_epf_configure_bar(epf, epc_features);
> > +	if (!epc_features) {
> > +		dev_err(&epf->dev, "epc_features not implemented\n");
> > +		return -EOPNOTSUPP;
> >  	}
> >
> > +	linkup_notifier = epc_features->linkup_notifier;
> > +	core_init_notifier = epc_features->core_init_notifier;
> > +	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;
> >
> > --
> > 2.7.4
> >