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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,
        syzbot+80899a8a8efe8968cde7@syzkaller.appspotmail.com,
        Rustam Kovhaev <rkovhaev@gmail.com>
Subject: [PATCH 5.4 15/67] staging: rtl8712: handle firmware load failure
Date:   Mon, 10 Aug 2020 17:21:02 +0200
Message-Id: <20200810151810.180199211@linuxfoundation.org>
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From: Rustam Kovhaev <rkovhaev@gmail.com>

commit b4383c971bc5263efe2b0915ba67ebf2bf3f1ee5 upstream.

when firmware fails to load we should not call unregister_netdev()
this patch fixes a race condition between rtl871x_load_fw_cb() and
r871xu_dev_remove() and fixes the bug reported by syzbot

Reported-by: syzbot+80899a8a8efe8968cde7@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=80899a8a8efe8968cde7
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200716151324.1036204-1-rkovhaev@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/rtl8712/hal_init.c |    3 ++-
 drivers/staging/rtl8712/usb_intf.c |   11 ++++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/staging/rtl8712/hal_init.c
+++ b/drivers/staging/rtl8712/hal_init.c
@@ -33,7 +33,6 @@ static void rtl871x_load_fw_cb(const str
 {
 	struct _adapter *adapter = context;
 
-	complete(&adapter->rtl8712_fw_ready);
 	if (!firmware) {
 		struct usb_device *udev = adapter->dvobjpriv.pusbdev;
 		struct usb_interface *usb_intf = adapter->pusb_intf;
@@ -41,11 +40,13 @@ static void rtl871x_load_fw_cb(const str
 		dev_err(&udev->dev, "r8712u: Firmware request failed\n");
 		usb_put_dev(udev);
 		usb_set_intfdata(usb_intf, NULL);
+		complete(&adapter->rtl8712_fw_ready);
 		return;
 	}
 	adapter->fw = firmware;
 	/* firmware available - start netdev */
 	register_netdev(adapter->pnetdev);
+	complete(&adapter->rtl8712_fw_ready);
 }
 
 static const char firmware_file[] = "rtlwifi/rtl8712u.bin";
--- a/drivers/staging/rtl8712/usb_intf.c
+++ b/drivers/staging/rtl8712/usb_intf.c
@@ -595,13 +595,17 @@ static void r871xu_dev_remove(struct usb
 	if (pnetdev) {
 		struct _adapter *padapter = netdev_priv(pnetdev);
 
-		usb_set_intfdata(pusb_intf, NULL);
-		release_firmware(padapter->fw);
 		/* never exit with a firmware callback pending */
 		wait_for_completion(&padapter->rtl8712_fw_ready);
+		pnetdev = usb_get_intfdata(pusb_intf);
+		usb_set_intfdata(pusb_intf, NULL);
+		if (!pnetdev)
+			goto firmware_load_fail;
+		release_firmware(padapter->fw);
 		if (drvpriv.drv_registered)
 			padapter->surprise_removed = true;
-		unregister_netdev(pnetdev); /* will call netdev_close() */
+		if (pnetdev->reg_state != NETREG_UNINITIALIZED)
+			unregister_netdev(pnetdev); /* will call netdev_close() */
 		flush_scheduled_work();
 		udelay(1);
 		/* Stop driver mlme relation timer */
@@ -614,6 +618,7 @@ static void r871xu_dev_remove(struct usb
 		 */
 		usb_put_dev(udev);
 	}
+firmware_load_fail:
 	/* If we didn't unplug usb dongle and remove/insert module, driver
 	 * fails on sitesurvey for the first time when device is up.
 	 * Reset usb port for sitesurvey fail issue.