[PATCH] powernv: eeh: fix possible buffer overrun in ioda_eeh_phb_diag()

[Gavin Shan]

On Thu, Dec 19, 2013 at 05:14:07PM -0600, Brian W Hart wrote:
>PHB diagnostic buffer may be smaller than PAGE_SIZE, especially when
>PAGE_SIZE > 4KB.
>

I think you're talking about that PAGE_SIZE could be configured
to have variable size (e.g. 4KB). So it's not safe to pass PAGE_SIZE
to OPAL API opal_pci_get_phb_diag_data2(). Instead, we should pass
PNV_PCI_DIAG_BUF_SIZE and it makes sense to me :-)

Also, it needs to be backported to stable kernel as well.

>Signed-off-by: Brian W Hart <hartb at linux.vnet.ibm.com>

Acked-by: Gavin Shan <shangw at linux.vnet.ibm.com>

>---
> arch/powerpc/platforms/powernv/eeh-ioda.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
>diff --git a/arch/powerpc/platforms/powernv/eeh-ioda.c b/arch/powerpc/platforms/powernv/eeh-ioda.c
>index 02245ce..8184ef5 100644
>--- a/arch/powerpc/platforms/powernv/eeh-ioda.c
>+++ b/arch/powerpc/platforms/powernv/eeh-ioda.c
>@@ -820,14 +820,15 @@ static void ioda_eeh_phb_diag(struct pci_controller *hose)
> 	struct OpalIoPhbErrorCommon *common;
> 	long rc;
>
>-	common = (struct OpalIoPhbErrorCommon *)phb->diag.blob;
>-	rc = opal_pci_get_phb_diag_data2(phb->opal_id, common, PAGE_SIZE);
>+	rc = opal_pci_get_phb_diag_data2(phb->opal_id, phb->diag.blob,
>+					 PNV_PCI_DIAG_BUF_SIZE);
> 	if (rc != OPAL_SUCCESS) {
> 		pr_warning("%s: Failed to get diag-data for PHB#%x (%ld)\n",
> 			    __func__, hose->global_number, rc);
> 		return;
> 	}
>
>+	common = (struct OpalIoPhbErrorCommon *)phb->diag.blob;
> 	switch (common->ioType) {
> 	case OPAL_PHB_ERROR_DATA_TYPE_P7IOC:
> 		ioda_eeh_p7ioc_phb_diag(hose, common);

Thanks,
Gavin