linux-kernel - [PATCH] PCI: endpoint: handle probable NULL pointer access

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Date:   Thu, 12 Oct 2017 09:27:57 +0530
From:   Pankaj Dubey <pankaj.dubey@...sung.com>
To:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Pankaj Dubey <pankaj.dubey@...sung.com>
Subject: [PATCH] PCI: endpoint: handle probable NULL pointer access

controller_group allocation in pci_ep_cfs_init function can fail
so we should have a check while using it in pci_ep_cfs_add_epc_group
for registering group, else we will hit NULL pointer access.

This patch adds required check for the same and returns -EPROBE_DEFER,
so that endpoint controller driver probe can be reattempted later
in case controller_group is not allocated because pci_ep_cfs_init is
not yet called.

Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com>
---
 drivers/pci/endpoint/pci-ep-cfs.c   | 7 ++++++-
 drivers/pci/endpoint/pci-epc-core.c | 4 ++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index 424fdd6..3cac818 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -172,7 +172,12 @@ struct config_group *pci_ep_cfs_add_epc_group(const char *name)
 	group = &epc_group->group;
 
 	config_group_init_type_name(group, name, &pci_epc_type);
-	ret = configfs_register_group(controllers_group, group);
+
+	if (controllers_group)
+		ret = configfs_register_group(controllers_group, group);
+	else
+		ret = -EPROBE_DEFER;
+
 	if (ret) {
 		pr_err("failed to register configfs group for %s\n", name);
 		goto err_register_group;
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 42c2a11..d327a2a 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -518,6 +518,10 @@ __pci_epc_create(struct device *dev, const struct pci_epc_ops *ops,
 		goto put_dev;
 
 	epc->group = pci_ep_cfs_add_epc_group(dev_name(dev));
+	if (IS_ERR(epc->group)) {
+		ret = -EPROBE_DEFER;
+		goto put_dev;
+	}
 
 	return epc;
 
-- 
2.7.4