From a01ba2a3378be85538e0183ae5367c1bc1d5aaf3 Mon Sep 17 00:00:00 2001
From: Jonathan Bell <jonathan@raspberrypi.com>
Date: Fri, 8 Oct 2021 12:25:43 +0300
Subject: [PATCH] xhci: guard accesses to ep_state in xhci_endpoint_reset()
Git-commit: a01ba2a3378be85538e0183ae5367c1bc1d5aaf3
Patch-mainline: v5.15-rc6
References: git-fixes stable-5.14.14

See https://github.com/raspberrypi/linux/issues/3981

Two read-modify-write cycles on ep->ep_state are not guarded by
xhci->lock. Fix these.

Fixes: f5249461b504 ("xhci: Clear the host side toggle manually when endpoint is soft reset")
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20211008092547.3996295-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/usb/host/xhci.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 93c38b557afd..541fe4dcc43a 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3214,10 +3214,13 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd,
 		return;
 
 	/* Bail out if toggle is already being cleared by a endpoint reset */
+	spin_lock_irqsave(&xhci->lock, flags);
 	if (ep->ep_state & EP_HARD_CLEAR_TOGGLE) {
 		ep->ep_state &= ~EP_HARD_CLEAR_TOGGLE;
+		spin_unlock_irqrestore(&xhci->lock, flags);
 		return;
 	}
+	spin_unlock_irqrestore(&xhci->lock, flags);
 	/* Only interrupt and bulk ep's use data toggle, USB2 spec 5.5.4-> */
 	if (usb_endpoint_xfer_control(&host_ep->desc) ||
 	    usb_endpoint_xfer_isoc(&host_ep->desc))
@@ -3303,8 +3306,10 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd,
 	xhci_free_command(xhci, cfg_cmd);
 cleanup:
 	xhci_free_command(xhci, stop_cmd);
+	spin_lock_irqsave(&xhci->lock, flags);
 	if (ep->ep_state & EP_SOFT_CLEAR_TOGGLE)
 		ep->ep_state &= ~EP_SOFT_CLEAR_TOGGLE;
+	spin_unlock_irqrestore(&xhci->lock, flags);
 }
 
 static int xhci_check_streams_endpoint(struct xhci_hcd *xhci,
-- 
2.26.2