linux-kernel - [PATCH] device_core: check null pointer

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Message-Id: <20251114141821.416835-1-xiazhengqiao@huaqin.corp-partner.google.com>
Date: Fri, 14 Nov 2025 22:18:21 +0800
From: Zhengqiao Xia <xiazhengqiao@...qin.corp-partner.google.com>
To: gregkh@...uxfoundation.org,
	rafael@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Zhengqiao Xia <xiazhengqiao@...qin.corp-partner.google.com>
Subject: [PATCH] device_core: check null pointer

Add null pointer check to avoid null pointer.
When the USB device's interface is disabled, 'device_add' will not
be called, and 'dev->p' will be NULL. When you use 'usbdev_ioctl' to
call this USB interface at this point,'__device_attach' will be invoked.
Then a null pointer will be generated.

Signed-off-by: Zhengqiao Xia <xiazhengqiao@...qin.corp-partner.google.com>
---
 drivers/base/dd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 3328101e0e106..cfdeb420fd12a 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1033,7 +1033,7 @@ static int __device_attach(struct device *dev, bool allow_async)
 	bool async = false;
 
 	device_lock(dev);
-	if (dev->p->dead) {
+	if (dev->p && dev->p->dead) {
 		goto out_unlock;
 	} else if (dev->driver) {
 		if (device_is_bound(dev)) {
-- 
2.34.1