linux-kernel - [PATCH 4.9 150/199] xhci: make sure interrupts are restored to correct state

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Date:   Thu, 19 Dec 2019 19:33:52 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 150/199] xhci: make sure interrupts are restored to correct state

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

[ Upstream commit bd82873f23c9a6ad834348f8b83f3b6a5bca2c65 ]

spin_unlock_irqrestore() might be called with stale flags after
reading port status, possibly restoring interrupts to a incorrect
state.

If a usb2 port just finished resuming while the port status is read
the spin lock will be temporary released and re-acquired in a separate
function. The flags parameter is passed as value instead of a pointer,
not updating flags properly before the final spin_unlock_irqrestore()
is called.

Cc: <stable@...r.kernel.org> # v3.12+
Fixes: 8b3d45705e54 ("usb: Fix xHCI host issues on remote wakeup.")
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Link: https://lore.kernel.org/r/20191211142007.8847-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/usb/host/xhci-hub.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 39e2d32710355..6777a81fb372b 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -728,7 +728,7 @@ static u32 xhci_get_port_status(struct usb_hcd *hcd,
 		struct xhci_bus_state *bus_state,
 		__le32 __iomem **port_array,
 		u16 wIndex, u32 raw_port_status,
-		unsigned long flags)
+		unsigned long *flags)
 	__releases(&xhci->lock)
 	__acquires(&xhci->lock)
 {
@@ -810,12 +810,12 @@ static u32 xhci_get_port_status(struct usb_hcd *hcd,
 			xhci_set_link_state(xhci, port_array, wIndex,
 					XDEV_U0);
 
-			spin_unlock_irqrestore(&xhci->lock, flags);
+			spin_unlock_irqrestore(&xhci->lock, *flags);
 			time_left = wait_for_completion_timeout(
 					&bus_state->rexit_done[wIndex],
 					msecs_to_jiffies(
 						XHCI_MAX_REXIT_TIMEOUT_MS));
-			spin_lock_irqsave(&xhci->lock, flags);
+			spin_lock_irqsave(&xhci->lock, *flags);
 
 			if (time_left) {
 				slot_id = xhci_find_slot_id_by_port(hcd,
@@ -961,7 +961,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			break;
 		}
 		status = xhci_get_port_status(hcd, bus_state, port_array,
-				wIndex, temp, flags);
+				wIndex, temp, &flags);
 		if (status == 0xffffffff)
 			goto error;
 
-- 
2.20.1