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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,
        "Woojung.Huh@microchip.com" <Woojung.Huh@microchip.com>,
        Johan Hovold <johan@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 32/56] net: lan78xx: add missing endpoint sanity check
Date:   Mon,  3 Aug 2020 14:19:47 +0200
Message-Id: <20200803121851.898829519@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

[ Upstream commit 8d8e95fd6d69d774013f51e5f2ee10c6e6d1fc14 ]

Add the missing endpoint sanity check to prevent a NULL-pointer
dereference should a malicious device lack the expected endpoints.

Note that the driver has a broken endpoint-lookup helper,
lan78xx_get_endpoints(), which can end up accepting interfaces in an
altsetting without endpoints as long as *some* altsetting has a bulk-in
and a bulk-out endpoint.

Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
Cc: Woojung.Huh@microchip.com <Woojung.Huh@microchip.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/usb/lan78xx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 92548887df2fe..2dff233814ea5 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -3786,6 +3786,11 @@ static int lan78xx_probe(struct usb_interface *intf,
 	netdev->max_mtu = MAX_SINGLE_PACKET_SIZE;
 	netif_set_gso_max_size(netdev, MAX_SINGLE_PACKET_SIZE - MAX_HEADER);
 
+	if (intf->cur_altsetting->desc.bNumEndpoints < 3) {
+		ret = -ENODEV;
+		goto out3;
+	}
+
 	dev->ep_blkin = (intf->cur_altsetting)->endpoint + 0;
 	dev->ep_blkout = (intf->cur_altsetting)->endpoint + 1;
 	dev->ep_intr = (intf->cur_altsetting)->endpoint + 2;
-- 
2.25.1