linux-kernel - [PATCH] PCI: endpoint: Fix NULL pointer dereference for ->get

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Date:   Wed, 11 Mar 2020 15:58:52 +0530
From:   Shradha Todi <shradha.t@...sung.com>
To:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     kishon@...com, lorenzo.pieralisi@....com, bhelgaas@...gle.com,
        pankaj.dubey@...sung.com, Shradha Todi <shradha.t@...sung.com>,
        Sriram Dash <sriram.dash@...sung.com>
Subject: [PATCH] PCI: endpoint: Fix NULL pointer dereference for
 ->get_features()

get_features ops of pci_epc_ops may return NULL, causing NULL pointer
dereference in pci_epf_test_bind function. Let us add a check for
pci_epc_feature pointer in pci_epf_test_bind before we access it to
avoid any such NULL pointer dereference and return -ENOTSUPP in case
pci_epc_feature is not found.

Reviewed-by: Pankaj Dubey <pankaj.dubey@...sung.com>
Signed-off-by: Sriram Dash <sriram.dash@...sung.com>
Signed-off-by: Shradha Todi <shradha.t@...sung.com>
---
 drivers/pci/endpoint/functions/pci-epf-test.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index c9121b1b9fa9..af4537a487bf 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -510,14 +510,17 @@ static int pci_epf_test_bind(struct pci_epf *epf)
 		return -EINVAL;
 
 	epc_features = pci_epc_get_features(epc, epf->func_no);
-	if (epc_features) {
-		linkup_notifier = epc_features->linkup_notifier;
-		msix_capable = epc_features->msix_capable;
-		msi_capable = epc_features->msi_capable;
-		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
-		pci_epf_configure_bar(epf, epc_features);
+	if (!epc_features) {
+		dev_err(dev, "epc_features not implemented\n");
+		return -ENOTSUPP;
 	}
 
+	linkup_notifier = epc_features->linkup_notifier;
+	msix_capable = epc_features->msix_capable;
+	msi_capable = epc_features->msi_capable;
+	test_reg_bar = pci_epc_get_first_free_bar(epc_features);
+	pci_epf_configure_bar(epf, epc_features);
+
 	epf_test->test_reg_bar = test_reg_bar;
 	epf_test->epc_features = epc_features;
 
-- 
2.17.1