netdev - [PATCH net v2] isdn: mISDN: hfcsusb: fix memory leak in hfcsusb

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Message-ID: <20251030042524.194812-1-nihaal@cse.iitm.ac.in>
Date: Thu, 30 Oct 2025 09:55:22 +0530
From: Abdun Nihaal <nihaal@....iitm.ac.in>
To: isdn@...ux-pingi.de
Cc: Abdun Nihaal <nihaal@....iitm.ac.in>,
	horms@...nel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net v2] isdn: mISDN: hfcsusb: fix memory leak in hfcsusb_probe()

In hfcsusb_probe(), the memory allocated for ctrl_urb gets leaked when
setup_instance() fails with an error code. Fix that by freeing the urb
before freeing the hw structure. Also change the error paths to use the
goto ladder style.

Compile tested only. Issue found using a prototype static analysis tool.

Fixes: 69f52adb2d53 ("mISDN: Add HFC USB driver")
Signed-off-by: Abdun Nihaal <nihaal@....iitm.ac.in>
---
v1->v2:
Updated to use the goto ladder for the error paths, and added a note on
testing and detection, as suggested by Simon Horman.

Link to v1:
https://patchwork.kernel.org/project/netdevbpf/patch/20251024173458.283837-1-nihaal@cse.iitm.ac.in/

 drivers/isdn/hardware/mISDN/hfcsusb.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index e54419a4e731..541a20cb58f1 100644
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -1904,13 +1904,13 @@ setup_instance(struct hfcsusb *hw, struct device *parent)
 	mISDN_freebchannel(&hw->bch[1]);
 	mISDN_freebchannel(&hw->bch[0]);
 	mISDN_freedchannel(&hw->dch);
-	kfree(hw);
 	return err;
 }
 
 static int
 hfcsusb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 {
+	int err;
 	struct hfcsusb			*hw;
 	struct usb_device		*dev = interface_to_usbdev(intf);
 	struct usb_host_interface	*iface = intf->cur_altsetting;
@@ -2101,20 +2101,28 @@ hfcsusb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	if (!hw->ctrl_urb) {
 		pr_warn("%s: No memory for control urb\n",
 			driver_info->vend_name);
-		kfree(hw);
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto err_free_hw;
 	}
 
 	pr_info("%s: %s: detected \"%s\" (%s, if=%d alt=%d)\n",
 		hw->name, __func__, driver_info->vend_name,
 		conf_str[small_match], ifnum, alt_used);
 
-	if (setup_instance(hw, dev->dev.parent))
-		return -EIO;
+	if (setup_instance(hw, dev->dev.parent)) {
+		err = -EIO;
+		goto err_free_urb;
+	}
 
 	hw->intf = intf;
 	usb_set_intfdata(hw->intf, hw);
 	return 0;
+
+err_free_urb:
+	usb_free_urb(hw->ctrl_urb);
+err_free_hw:
+	kfree(hw);
+	return err;
 }
 
 /* function called when an active device is removed */
-- 
2.43.0