Re: [PATCH] PCI: endpoint: pci-epf-vntb: Use array_index_nospec() on mws_size[] access
From: Koichiro Den
Date: Tue Feb 17 2026 - 23:47:54 EST
On Tue, Feb 17, 2026 at 07:20:23PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Jan 05, 2026 at 04:56:06PM +0900, Koichiro Den wrote:
> > Follow common kernel idioms for indices derived from configfs attributes
> > and suppress Smatch warnings:
> >
> > epf_ntb_mw1_show() warn: potential spectre issue 'ntb->mws_size' [r]
> > epf_ntb_mw1_store() warn: potential spectre issue 'ntb->mws_size' [w]
> >
> > Also fix the error message for out-of-range MW indices and %lld format
> > for unsigned values.
> >
> > Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> > Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> > ---
> > Base: https://github.com/jonmason/ntb/commit/68113d260674 (ntb-next)
> > This is a spin-off patch from the following series:
> > https://lore.kernel.org/all/20251217151609.3162665-2-den@xxxxxxxxxxxxx/
> >
> > drivers/pci/endpoint/functions/pci-epf-vntb.c | 24 +++++++++++--------
> > 1 file changed, 14 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > index 83e9ab10f9c4..192dd4f4de8d 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > @@ -876,17 +876,19 @@ static ssize_t epf_ntb_##_name##_show(struct config_item *item, \
> > struct config_group *group = to_config_group(item); \
> > struct epf_ntb *ntb = to_epf_ntb(group); \
> > struct device *dev = &ntb->epf->dev; \
> > - int win_no; \
> > + int win_no, idx; \
> > \
> > if (sscanf(#_name, "mw%d", &win_no) != 1) \
> > return -EINVAL; \
> > \
> > - if (win_no <= 0 || win_no > ntb->num_mws) { \
> > - dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \
> > + idx = win_no - 1; \
> > + if (idx < 0 || idx >= ntb->num_mws) { \
> > + dev_err(dev, "MW%d out of range (num_mws=%d)\n", \
> > + win_no, ntb->num_mws); \
> > return -EINVAL; \
>
> This should be -ERANGE, but in a separate patch.
>
> > } \
> > - \
> > - return sprintf(page, "%lld\n", ntb->mws_size[win_no - 1]); \
> > + idx = array_index_nospec(idx, ntb->num_mws); \
> > + return sprintf(page, "%llu\n", ntb->mws_size[idx]); \
> > }
> >
> > #define EPF_NTB_MW_W(_name) \
> > @@ -896,7 +898,7 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> > struct config_group *group = to_config_group(item); \
> > struct epf_ntb *ntb = to_epf_ntb(group); \
> > struct device *dev = &ntb->epf->dev; \
> > - int win_no; \
> > + int win_no, idx; \
> > u64 val; \
> > int ret; \
> > \
> > @@ -907,12 +909,14 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
> > if (sscanf(#_name, "mw%d", &win_no) != 1) \
> > return -EINVAL; \
> > \
> > - if (win_no <= 0 || win_no > ntb->num_mws) { \
> > - dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \
> > + idx = win_no - 1; \
> > + if (idx < 0 || idx >= ntb->num_mws) { \
> > + dev_err(dev, "MW%d out of range (num_mws=%d)\n", \
> > + win_no, ntb->num_mws); \
> > return -EINVAL; \
>
> Same here.
>
> - Mani
Thanks for the comment. I will send a separate patch for that.
Before doing so, I have a quick question regarding the routing of pci-epf-vntb
patches.
Commit e4fe2a2fc423 ("MAINTAINERS: add PCI Endpoint NTB drivers to NTB files")
places pci-epf-vntb under the NTB subsystem. However, I'm not entirely sure
which tree (NTB or PCI EP) is expected to take changes to pci-epf-vntb.
Should updates be based on the NTB tree or the PCI EP tree?
Sorry if this has already been clarified and I just overlooked it.
Best regards,
Koichiro
>
> > } \
> > - \
> > - ntb->mws_size[win_no - 1] = val; \
> > + idx = array_index_nospec(idx, ntb->num_mws); \
> > + ntb->mws_size[idx] = val; \
> > \
> > return len; \
> > }
> > --
> > 2.51.0
> >
>
> --
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