linux-kernel - [PATCH] PCI/hotplug: fix potential null pointer deference

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Date:   Fri, 14 Jun 2019 20:41:25 +0800
From:   Young Xiao <92siuyang@...il.com>
To:     bhelgaas@...gle.com, tyreld@...ux.vnet.ibm.com,
        andy.shevchenko@...il.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Young Xiao <92siuyang@...il.com>
Subject: [PATCH] PCI/hotplug: fix potential null pointer deference

There is otherwise a risk of a null pointer dereference.

Signed-off-by: Young Xiao <92siuyang@...il.com>
---
 drivers/pci/hotplug/cpqphp_ctrl.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/hotplug/cpqphp_ctrl.c b/drivers/pci/hotplug/cpqphp_ctrl.c
index b7f4e1f..3c8399f 100644
--- a/drivers/pci/hotplug/cpqphp_ctrl.c
+++ b/drivers/pci/hotplug/cpqphp_ctrl.c
@@ -598,10 +598,11 @@ static struct pci_resource *get_io_resource(struct pci_resource **head, u32 size
 			*head = node->next;
 		} else {
 			prevnode = *head;
-			while (prevnode->next != node)
+			while (prevnode && prevnode->next != node)
 				prevnode = prevnode->next;
 
-			prevnode->next = node->next;
+			if (prevnode)
+				prevnode->next = node->next;
 		}
 		node->next = NULL;
 		break;
@@ -788,10 +789,11 @@ static struct pci_resource *get_resource(struct pci_resource **head, u32 size)
 			*head = node->next;
 		} else {
 			prevnode = *head;
-			while (prevnode->next != node)
+			while (prevnode && prevnode->next != node)
 				prevnode = prevnode->next;
 
-			prevnode->next = node->next;
+			if (prevnode)
+				prevnode->next = node->next;
 		}
 		node->next = NULL;
 		break;
-- 
2.7.4