linux-kernel - [PATCH] fpga: dfl: pci: gracefully handle misconfigured port entries

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Date:   Tue, 20 Apr 2021 10:27:40 -0700
From:   matthew.gerlach@...ux.intel.com
To:     hao.wu@...el.com, trix@...hat.com, linux-fpga@...r.kernel.org,
        linux-kernel@...r.kernel.org, yilun.xu@...el.com,
        russell.h.weight@...el.com, mdf@...nel.org
Cc:     Matthew Gerlach <matthew.gerlach@...ux.intel.com>
Subject: [PATCH] fpga: dfl: pci: gracefully handle misconfigured port entries

From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>

Gracefully ignore misconfigured port entries encountered in
incorrect FPGA images.

Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
---
 drivers/fpga/dfl-pci.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
index b44523e..660d3b6 100644
--- a/drivers/fpga/dfl-pci.c
+++ b/drivers/fpga/dfl-pci.c
@@ -212,6 +212,7 @@ static int find_dfls_by_default(struct pci_dev *pcidev,
 	int port_num, bar, i, ret = 0;
 	resource_size_t start, len;
 	void __iomem *base;
+	int bars = 0;
 	u32 offset;
 	u64 v;
 
@@ -228,6 +229,7 @@ static int find_dfls_by_default(struct pci_dev *pcidev,
 	if (dfl_feature_is_fme(base)) {
 		start = pci_resource_start(pcidev, 0);
 		len = pci_resource_len(pcidev, 0);
+		bars |= BIT(0);
 
 		dfl_fpga_enum_info_add_dfl(info, start, len);
 
@@ -253,9 +255,21 @@ static int find_dfls_by_default(struct pci_dev *pcidev,
 			 */
 			bar = FIELD_GET(FME_PORT_OFST_BAR_ID, v);
 			offset = FIELD_GET(FME_PORT_OFST_DFH_OFST, v);
+			if (bars & BIT(bar)) {
+				dev_warn(&pcidev->dev, "skipping bad port BAR %d\n", bar);
+				continue;
+			}
+
 			start = pci_resource_start(pcidev, bar) + offset;
-			len = pci_resource_len(pcidev, bar) - offset;
+			len = pci_resource_len(pcidev, bar);
+			if (offset >= len) {
+				dev_warn(&pcidev->dev, "bad port offset %u >= %pa\n",
+					 offset, &len);
+				continue;
+			}
 
+			len -= offset;
+			bars |= BIT(bar);
 			dfl_fpga_enum_info_add_dfl(info, start, len);
 		}
 	} else if (dfl_feature_is_port(base)) {
-- 
1.8.3.1