linux-kernel - [PATCH] udc: Memory leak on error path and use after free

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Date:   Wed, 16 Aug 2017 16:47:28 +0300
From:   Anton Vasilyev <vasilyev@...ras.ru>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     Anton Vasilyev <vasilyev@...ras.ru>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Jussi Kivilinna <jussi.kivilinna@...tian.com>,
        Peter Senna Tschudin <peter.senna@...labora.com>,
        Raz Manor <Raz.Manor@...ens.com>,
        Romain Perier <romain.perier@...labora.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: [PATCH] udc: Memory leak on error path and use after free

gadget_release() is responsible for cleanup dev memory.
But if net2280_probe() fails after dev allocation, then
gadget_release() become unregistered and dev memory leaks.
Also net2280_remove() calls usb_del_gadget_udc() which
perform schedule_delayed_work() with gadget_release(), so
it is possible that dev will be deallocated exactly after
this call and leads to use after free.

The patch moves deallocation from gadget_release() to
net2280_remove().

Found by Linux Driver Verififcation project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@...ras.ru>
---
 drivers/usb/gadget/udc/net2280.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
index f608c1f..62ac876 100644
--- a/drivers/usb/gadget/udc/net2280.c
+++ b/drivers/usb/gadget/udc/net2280.c
@@ -3546,15 +3546,6 @@ static irqreturn_t net2280_irq(int irq, void *_dev)
 	return IRQ_HANDLED;
 }
 
-/*-------------------------------------------------------------------------*/
-
-static void gadget_release(struct device *_dev)
-{
-	struct net2280	*dev = dev_get_drvdata(_dev);
-
-	kfree(dev);
-}
-
 /* tear down the binding between this driver and the pci device */
 
 static void net2280_remove(struct pci_dev *pdev)
@@ -3592,6 +3583,8 @@ static void net2280_remove(struct pci_dev *pdev)
 	device_remove_file(&pdev->dev, &dev_attr_registers);
 
 	ep_info(dev, "unbind\n");
+
+	kfree(dev);
 }
 
 /* wrap this driver around the specified device, but
@@ -3769,8 +3762,7 @@ static int net2280_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (retval)
 		goto done;
 
-	retval = usb_add_gadget_udc_release(&pdev->dev, &dev->gadget,
-			gadget_release);
+	retval = usb_add_gadget_udc(&pdev->dev, &dev->gadget);
 	if (retval)
 		goto done;
 	return 0;
-- 
2.7.4