FAILED: patch "[PATCH] usb: dwc3: gadget: Fix NULL pointer dereference in" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x 61a348857e869432e6a920ad8ea9132e8d44c316
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024021815-crate-unsettled-85a8@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

61a348857e86 ("usb: dwc3: gadget: Fix NULL pointer dereference in dwc3_gadget_suspend")
c8540870af4c ("usb: dwc3: gadget: Improve dwc3_gadget_suspend() and dwc3_gadget_resume()")
bdb19d01026a ("USB: dwc3: gadget: drop dead hibernation code")
af870d93c706 ("usb: dwc3: Fix typos in gadget.c")
5265397f9442 ("usb: dwc3: Remove DWC3 locking during gadget suspend/resume")
9711c67de748 ("usb: dwc3: gadget: Synchronize IRQ between soft connect/disconnect")
8f8034f493b5 ("usb: dwc3: gadget: Don't modify GEVNTCOUNT in pullup()")
861c010a2ee1 ("usb: dwc3: gadget: Refactor pullup()")
0066472de157 ("usb: dwc3: Issue core soft reset before enabling run/stop")
8217f07a5023 ("usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind")
8212937305f8 ("usb: dwc3: gadget: Disable gadget IRQ during pullup disable")
f09ddcfcb8c5 ("usb: dwc3: gadget: Prevent EP queuing while stopping transfers")
a66a7d48f34a ("Merge 5.11-rc3 into usb-next")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 61a348857e869432e6a920ad8ea9132e8d44c316 Mon Sep 17 00:00:00 2001
From: Uttkarsh Aggarwal <quic_uaggarwa@quicinc.com>
Date: Fri, 19 Jan 2024 15:18:25 +0530
Subject: [PATCH] usb: dwc3: gadget: Fix NULL pointer dereference in
 dwc3_gadget_suspend

In current scenario if Plug-out and Plug-In performed continuously
there could be a chance while checking for dwc->gadget_driver in
dwc3_gadget_suspend, a NULL pointer dereference may occur.

Call Stack:

	CPU1:                           CPU2:
	gadget_unbind_driver            dwc3_suspend_common
	dwc3_gadget_stop                dwc3_gadget_suspend
                                        dwc3_disconnect_gadget

CPU1 basically clears the variable and CPU2 checks the variable.
Consider CPU1 is running and right before gadget_driver is cleared
and in parallel CPU2 executes dwc3_gadget_suspend where it finds
dwc->gadget_driver which is not NULL and resumes execution and then
CPU1 completes execution. CPU2 executes dwc3_disconnect_gadget where
it checks dwc->gadget_driver is already NULL because of which the
NULL pointer deference occur.

Cc: stable@vger.kernel.org
Fixes: 9772b47a4c29 ("usb: dwc3: gadget: Fix suspend/resume during device mode")
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Uttkarsh Aggarwal <quic_uaggarwa@quicinc.com>
Link: https://lore.kernel.org/r/20240119094825.26530-1-quic_uaggarwa@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 019368f8e9c4..564976b3e2b9 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4709,15 +4709,13 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
 	unsigned long flags;
 	int ret;
 
-	if (!dwc->gadget_driver)
-		return 0;
-
 	ret = dwc3_gadget_soft_disconnect(dwc);
 	if (ret)
 		goto err;
 
 	spin_lock_irqsave(&dwc->lock, flags);
-	dwc3_disconnect_gadget(dwc);
+	if (dwc->gadget_driver)
+		dwc3_disconnect_gadget(dwc);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;