patch "USB: UDC core: fix double-free in usb_add_gadget_udc_release" added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    USB: UDC core: fix double-free in usb_add_gadget_udc_release

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 7ae2c3c280db183ca9ada2675c34ec2f7378abfa Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Wed, 3 Jan 2018 12:51:51 -0500
Subject: USB: UDC core: fix double-free in usb_add_gadget_udc_release

The error-handling pathways in usb_add_gadget_udc_release() are messed
up.  Aside from the uninformative statement labels, they can deallocate
the udc structure after calling put_device(), which is a double-free.
This was observed by KASAN in automatic testing.

This patch cleans up the routine.  It preserves the requirement that
when any failure occurs, we call put_device(&gadget->dev).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
CC: <stable@vger.kernel.org>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/gadget/udc/core.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 93eff7dec2f5..1b3efb14aec7 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1147,11 +1147,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 
 	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
 	if (!udc)
-		goto err1;
-
-	ret = device_add(&gadget->dev);
-	if (ret)
-		goto err2;
+		goto err_put_gadget;
 
 	device_initialize(&udc->dev);
 	udc->dev.release = usb_udc_release;
@@ -1160,7 +1156,11 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 	udc->dev.parent = parent;
 	ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
 	if (ret)
-		goto err3;
+		goto err_put_udc;
+
+	ret = device_add(&gadget->dev);
+	if (ret)
+		goto err_put_udc;
 
 	udc->gadget = gadget;
 	gadget->udc = udc;
@@ -1170,7 +1170,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 
 	ret = device_add(&udc->dev);
 	if (ret)
-		goto err4;
+		goto err_unlist_udc;
 
 	usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
 	udc->vbus = true;
@@ -1178,27 +1178,25 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 	/* pick up one of pending gadget drivers */
 	ret = check_pending_gadget_drivers(udc);
 	if (ret)
-		goto err5;
+		goto err_del_udc;
 
 	mutex_unlock(&udc_lock);
 
 	return 0;
 
-err5:
+ err_del_udc:
 	device_del(&udc->dev);
 
-err4:
+ err_unlist_udc:
 	list_del(&udc->list);
 	mutex_unlock(&udc_lock);
 
-err3:
-	put_device(&udc->dev);
 	device_del(&gadget->dev);
 
-err2:
-	kfree(udc);
+ err_put_udc:
+	put_device(&udc->dev);
 
-err1:
+ err_put_gadget:
 	put_device(&gadget->dev);
 	return ret;
 }
-- 
2.15.1