[PATCH] usb: host: xhci-tegra: Unregister OTG notifier before cancelling id_work

[Myeonghun Pak]

tegra_xusb_remove() cancels id_work, then calls otg_set_host() with a
NULL host.  That leaves id_nb registered until devm_usb_phy_release2()
runs after .remove() returns, so a role change can queue id_work again
and use the HCD released by usb_put_hcd().

Unregister id_nb first.  atomic_notifier_chain_unregister() finishes
callbacks already on the chain, and cancel_work_sync() drains the work
they queued.  devm_usb_phy_release2() unregisters again.  A second
unregister finds no entry; the wrapper discards the internal -ENOENT.
The devres entry is still required for usb_put_phy().

This issue was identified during our ongoing static-analysis research
while reviewing kernel code.

Fixes: f836e7843036 ("usb: xhci-tegra: Add OTG support")
Cc: stable@xxxxxxxxxxxxxxx # 5.7+
Assisted-by: LLM
Co-developed-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Myeonghun Pak <mhun512@xxxxxxxxx>
---
 drivers/usb/host/xhci-tegra.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index 6f235d1e117e..f5894f2a5991 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -1542,11 +1542,20 @@ static void tegra_xusb_deinit_usb_phy(struct tegra_xusb *tegra)
 {
 	unsigned int i;
 
-	cancel_work_sync(&tegra->id_work);
-
-	for (i = 0; i < tegra->num_usb_phys; i++)
-		if (tegra->usbphy[i])
+	/*
+	 * id_nb is registered on the PHY notifier chain by
+	 * devm_usb_get_phy_by_node(), so devres would only drop it after
+	 * tegra_xusb_remove() has returned.  Unregister it here, before the
+	 * work is cancelled, so that it cannot be queued again.
+	 */
+	for (i = 0; i < tegra->num_usb_phys; i++) {
+		if (tegra->usbphy[i]) {
+			usb_unregister_notifier(tegra->usbphy[i], &tegra->id_nb);
 			otg_set_host(tegra->usbphy[i]->otg, NULL);
+		}
+	}
+
+	cancel_work_sync(&tegra->id_work);
 }
 
 static int tegra_xusb_setup_wakeup(struct platform_device *pdev, struct tegra_xusb *tegra)

base-commit: 238650ef6c7c7cca08e032527329424c9fbd70e5
-- 
2.53.0