[PATCH 1/2] PCI: endpoint: pci-epf-vntb: Add check to detect 'db_count' value of 0

[Manivannan Sadhasivam]

From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>

epf_ntb::db_count value should be within 1 to MAX_DB_COUNT. Current code
only checks for the upper bound, while the lower bound is unchecked. This
can cause a lot of issues in the driver if the user passes 'db_count' as 0.

So add a check for 0 also. While at it, remove the redundant 'db_count'
assignment.

Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>
---
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 2256c3062b1a..3d30aa4dbb84 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -483,7 +483,6 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
 {
 	const struct pci_epc_features *epc_features;
 	struct device *dev;
-	u32 db_count;
 	int ret;
 
 	dev = &ntb->epf->dev;
@@ -495,14 +494,12 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
 		return -EINVAL;
 	}
 
-	db_count = ntb->db_count;
-	if (db_count > MAX_DB_COUNT) {
-		dev_err(dev, "DB count cannot be more than %d\n", MAX_DB_COUNT);
+	if (!ntb->db_count || ntb->db_count > MAX_DB_COUNT) {
+		dev_err(dev, "DB count %d out of range (1 - %d)\n",
+			ntb->db_count, MAX_DB_COUNT);
 		return -EINVAL;
 	}
 
-	ntb->db_count = db_count;
-
 	if (epc_features->msi_capable) {
 		ret = pci_epc_set_msi(ntb->epf->epc,
 				      ntb->epf->func_no,
-- 
2.51.0