linux-kernel - [PATCH 1/2] Revert "usb: dwc3: gadget: Fix incorrect UDC state after manual deconfiguration"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250301003452.2675360-2-quic_wcheng@quicinc.com>
Date: Fri, 28 Feb 2025 16:34:51 -0800
From: Wesley Cheng <quic_wcheng@...cinc.com>
To: <gregkh@...uxfoundation.org>, <Thinh.Nguyen@...opsys.com>
CC: <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        Wesley Cheng
	<quic_wcheng@...cinc.com>
Subject: [PATCH 1/2] Revert "usb: dwc3: gadget: Fix incorrect UDC state after manual deconfiguration"

This reverts commit 1ff24d40b3c3c673d833c546f898133b80dffc39.

The following change creates a potential use after freed scenario within
the UDC core level.  When transitioning from peripheral to host mode, the
DWC3 DRD will remove the USB UDC using usb_del_gadget().  As part of the
UDC removal routine, the UDC core will issue a pullup disable call back to
the DWC3 gadget driver, which will now call usb_gadget_set_state(), and
queues gadget->work.  If gadget->work is unable to complete before the USB
gadget is freed, then we will run into the use after freed situation.

Below is the callstack in question:

dwc3_gadget_exit()
 --> usb_del_gadget()
 --> gadget_unbind_driver()
  --> device_del()
   --> gadget_unbind_driver()
    --> usb_gadget_disconnect_locked()
     --> pullup(0)
      --> dwc3_gadget_soft_disconnect()
       --> usb_gadget_set_state(UNATTACHED)
        --> queue_work(gadget->work) --> async
  --> device_unregister()

Unfortunately, the flush_work() call within usb_del_gadget() doesn't work
in this situation, as it happens before the device_del() and soft
disconnect sequence.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/dwc3/gadget.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 5156fafbda6c..921f72995dbf 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2781,8 +2781,6 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
 	__dwc3_gadget_stop(dwc);
 	spin_unlock_irqrestore(&dwc->lock, flags);

-	usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
-
 	return ret;
 }