linux-kernel - [PATCH] xen/xenbus: handle pointer to NULL in alloc/free

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Date: Wed, 29 May 2024 22:19:28 +0900
From: yskelg@...il.com
To: Stefano Stabellini <sstabellini@...nel.org>,
	Juergen Gross <jgross@...e.com>,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
Cc: skhan@...uxfoundation.org,
	sj@...nel.org,
	Austin Kim <austindh.kim@...il.com>,
	shjy180909@...il.com,
	linux-kernel@...r.kernel.org,
	xen-devel@...ts.xenproject.org,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	Yunseong Kim <yskelg@...il.com>
Subject: [PATCH] xen/xenbus: handle pointer to NULL in alloc/free_pdev

From: Yunseong Kim <yskelg@...il.com>

Modify 'alloc_pdev()' to set 'pdev->xdev' to NULL
if 'xen_pcibk_init_devices()' fails. This ensures that 'pdev->xdev' does
not point to 'xdev' when 'pdev' is freed.
And modify 'free_pdev()' to set 'pdev' to NULL.

Signed-off-by: Yunseong Kim <yskelg@...il.com>
---
 drivers/xen/xen-pciback/xenbus.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index b11e401f1b1e..f1709b8e284a 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -54,6 +54,7 @@ static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
 	INIT_WORK(&pdev->op_work, xen_pcibk_do_op);
 
 	if (xen_pcibk_init_devices(pdev)) {
+		pdev->xdev = NULL;
 		kfree(pdev);
 		pdev = NULL;
 	}
@@ -102,6 +103,7 @@ static void free_pdev(struct xen_pcibk_device *pdev)
 	pdev->xdev = NULL;
 
 	kfree(pdev);
+	pdev = NULL;
 }
 
 static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
-- 
2.34.1