Re: [PATCH] PCI: endpoint: pci-epf-vntb: Check pci_epc_get_features() return value

On Tue, Feb 24, 2026 at 05:31:03AM -0800, Alok Tiwari wrote:
> pci_epc_get_features() may return NULL for invalid function numbers or
> if the EPC driver does not provide feature information. Other EPF drivers
> such as pci-epf-ntb.c and pci-epf-test.c already handle this case.
> 
> Add a defensive NULL check to avoid a potential NULL pointer dereference.
> 
> No functional change intended.
> 
> Signed-off-by: Alok Tiwari <[email protected]>
> ---
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 8 ++++++++
>  1 file changed, 8 insertions(+)

Hi Alok,

Thanks for picking this up. I have a similar view to Niklas [1], so if you
agree, I'll wait for a respin.
[1] https://lore.kernel.org/linux-pci/hew5wbd4fkaqlykv763wss3jirv52b5fyypzirvywysldbw5hh@qpds3syxgxgc/

Best regards,
Koichiro

> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 20a400e83439..93943e4497a6 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -438,6 +438,8 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb)
>  	const struct pci_epc_features *epc_features = pci_epc_get_features(epf->epc,
>  								epf->func_no,
>  								epf->vfunc_no);
> +	if (!epc_features)
> +		return -EINVAL;
>  	barno = ntb->epf_ntb_bar[BAR_CONFIG];
>  	spad_count = ntb->spad_count;
>  
> @@ -489,6 +491,8 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
>  	dev = &ntb->epf->dev;
>  
>  	epc_features = pci_epc_get_features(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no);
> +	if (!epc_features)
> +		return -EINVAL;
>  
>  	if (!(epc_features->msix_capable || epc_features->msi_capable)) {
>  		dev_err(dev, "MSI or MSI-X is required for doorbell\n");
> @@ -624,6 +628,8 @@ static int epf_ntb_db_bar_init(struct epf_ntb *ntb)
>  	epc_features = pci_epc_get_features(ntb->epf->epc,
>  					    ntb->epf->func_no,
>  					    ntb->epf->vfunc_no);
> +	if (!epc_features)
> +		return -EINVAL;
>  	barno = ntb->epf_ntb_bar[BAR_DB];
>  	epf_bar = &ntb->epf->bar[barno];
>  
> @@ -852,6 +858,8 @@ static int epf_ntb_init_epc_bar(struct epf_ntb *ntb)
>  	num_mws = ntb->num_mws;
>  	dev = &ntb->epf->dev;
>  	epc_features = pci_epc_get_features(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no);
> +	if (!epc_features)
> +		return -EINVAL;
>  
>  	/* These are required BARs which are mandatory for NTB functionality */
>  	for (bar = BAR_CONFIG; bar <= BAR_MW1; bar++) {
> -- 
> 2.50.1
>