linux-kernel - [PATCH 1/2] staging: gpib: Fix NULL pointer dereference in detach

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Message-ID: <20250118145046.12181-2-dpenkler@gmail.com>
Date: Sat, 18 Jan 2025 15:50:45 +0100
From: Dave Penkler <dpenkler@...il.com>
To: gregkh@...uxfoundation.org,
	linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Dave Penkler <dpenkler@...il.com>
Subject: [PATCH 1/2] staging: gpib: Fix NULL pointer dereference in detach

When the detach function is called after a failed attach
the usb_dev initialization can cause a NULL pointer
dereference. This happens when the usb device is not found
in the attach procedure.

Remove the usb_dev variable and initialization and change the dev
in the dev_info message from the usb_dev to the gpib_dev.

Fixes: fbae7090f30c ("staging: gpib: Update messaging and usb_device refs in agilent_usb")
Signed-off-by: Dave Penkler <dpenkler@...il.com>
---
 drivers/staging/gpib/agilent_82357a/agilent_82357a.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/staging/gpib/agilent_82357a/agilent_82357a.c b/drivers/staging/gpib/agilent_82357a/agilent_82357a.c
index 34d85a1bdb37..2aaccebc3c7b 100644
--- a/drivers/staging/gpib/agilent_82357a/agilent_82357a.c
+++ b/drivers/staging/gpib/agilent_82357a/agilent_82357a.c
@@ -1442,12 +1442,10 @@ static int agilent_82357a_go_idle(gpib_board_t *board)
 static void agilent_82357a_detach(gpib_board_t *board)
 {
 	struct agilent_82357a_priv *a_priv;
-	struct usb_device *usb_dev;
 
 	mutex_lock(&agilent_82357a_hotplug_lock);
 
 	a_priv = board->private_data;
-	usb_dev = interface_to_usbdev(a_priv->bus_interface);
 	if (a_priv) {
 		if (a_priv->bus_interface) {
 			agilent_82357a_go_idle(board);
@@ -1459,7 +1457,7 @@ static void agilent_82357a_detach(gpib_board_t *board)
 		agilent_82357a_cleanup_urbs(a_priv);
 		agilent_82357a_free_private(a_priv);
 	}
-	dev_info(&usb_dev->dev, "%s: detached\n", __func__);
+	dev_info(board->gpib_dev, "%s: detached\n", __func__);
 	mutex_unlock(&agilent_82357a_hotplug_lock);
 }
 
-- 
2.47.1