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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, Jes Sorensen <Jes.Sorensen@redhat.com>,
        Johan Hovold <johan@kernel.org>,
        Kalle Valo <kvalo@codeaurora.org>
Subject: [PATCH 4.19 21/55] rtl8xxxu: fix interface sanity check
Date:   Thu, 30 Jan 2020 19:39:02 +0100
Message-Id: <20200130183612.657914937@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit 39a4281c312f2d226c710bc656ce380c621a2b16 upstream.

Make sure to use the current alternate setting when verifying the
interface descriptors to avoid binding to an invalid interface.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 26f1fad29ad9 ("New driver: rtl8xxxu (mac80211)")
Cc: stable <stable@vger.kernel.org>     # 4.4
Cc: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
@@ -5921,7 +5921,7 @@ static int rtl8xxxu_parse_usb(struct rtl
 	u8 dir, xtype, num;
 	int ret = 0;
 
-	host_interface = &interface->altsetting[0];
+	host_interface = interface->cur_altsetting;
 	interface_desc = &host_interface->desc;
 	endpoints = interface_desc->bNumEndpoints;