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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jonathan Bell <jonathan@raspberrypi.com>,
        Mathias Nyman <mathias.nyman@linux.intel.com>
Subject: [PATCH 5.4 19/69] xhci: guard accesses to ep_state in xhci_endpoint_reset()
Date:   Mon, 18 Oct 2021 15:24:17 +0200
Message-Id: <20211018132330.106182147@linuxfoundation.org>
In-Reply-To: <20211018132329.453964125@linuxfoundation.org>
References: <20211018132329.453964125@linuxfoundation.org>
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From: Jonathan Bell <jonathan@raspberrypi.com>

commit a01ba2a3378be85538e0183ae5367c1bc1d5aaf3 upstream.

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

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3173,10 +3173,13 @@ static void xhci_endpoint_reset(struct u
 		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))
@@ -3262,8 +3265,10 @@ static void xhci_endpoint_reset(struct u
 	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,