linux-kernel - [PATCH 5.4 155/215] USB: c67x00: fix use after free in c67x00_giveback

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Message-Id: <20200720152827.562715151@linuxfoundation.org>
Date:   Mon, 20 Jul 2020 17:37:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tom Rix <trix@...hat.com>
Subject: [PATCH 5.4 155/215] USB: c67x00: fix use after free in c67x00_giveback_urb

From: Tom Rix <trix@...hat.com>

commit 211f08347355cba1f769bbf3355816a12b3ddd55 upstream.

clang static analysis flags this error

c67x00-sched.c:489:55: warning: Use of memory after it is freed [unix.Malloc]
        usb_hcd_giveback_urb(c67x00_hcd_to_hcd(c67x00), urb, urbp->status);
                                                             ^~~~~~~~~~~~
Problem happens in this block of code

	c67x00_release_urb(c67x00, urb);
	usb_hcd_unlink_urb_from_ep(c67x00_hcd_to_hcd(c67x00), urb);
	spin_unlock(&c67x00->lock);
	usb_hcd_giveback_urb(c67x00_hcd_to_hcd(c67x00), urb, urbp->status);

In the call to c67x00_release_urb has this freeing of urbp

	urbp = urb->hcpriv;
	urb->hcpriv = NULL;
	list_del(&urbp->hep_node);
	kfree(urbp);

And so urbp is freed before usb_hcd_giveback_urb uses it as its 3rd
parameter.

Since all is required is the status, pass the status directly as is
done in c64x00_urb_dequeue

Fixes: e9b29ffc519b ("USB: add Cypress c67x00 OTG controller HCD driver")
Signed-off-by: Tom Rix <trix@...hat.com>
Cc: stable <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20200708131243.24336-1-trix@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/c67x00/c67x00-sched.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/c67x00/c67x00-sched.c
+++ b/drivers/usb/c67x00/c67x00-sched.c
@@ -486,7 +486,7 @@ c67x00_giveback_urb(struct c67x00_hcd *c
 	c67x00_release_urb(c67x00, urb);
 	usb_hcd_unlink_urb_from_ep(c67x00_hcd_to_hcd(c67x00), urb);
 	spin_unlock(&c67x00->lock);
-	usb_hcd_giveback_urb(c67x00_hcd_to_hcd(c67x00), urb, urbp->status);
+	usb_hcd_giveback_urb(c67x00_hcd_to_hcd(c67x00), urb, status);
 	spin_lock(&c67x00->lock);
 }