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From:   Johan Hovold <johan@kernel.org>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     linux-input@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, Johan Hovold <johan@kernel.org>,
        stable <stable@vger.kernel.org>,
        Martin Kepplinger <martink@posteo.de>
Subject: [PATCH 1/7] Input: pegasus_notetaker: fix endpoint sanity check
Date:   Tue, 10 Dec 2019 12:37:31 +0100
Message-Id: <20191210113737.4016-2-johan@kernel.org>
In-Reply-To: <20191210113737.4016-1-johan@kernel.org>
References: <20191210113737.4016-1-johan@kernel.org>
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The driver was checking the number of endpoints of the first alternate
setting instead of the current one, something which could be used by a
malicious device (or USB descriptor fuzzer) to trigger a NULL-pointer
dereference.

Fixes: 1afca2b66aac ("Input: add Pegasus Notetaker tablet driver")
Cc: stable <stable@vger.kernel.org>     # 4.8
Cc: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/input/tablet/pegasus_notetaker.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/tablet/pegasus_notetaker.c b/drivers/input/tablet/pegasus_notetaker.c
index a1f3a0cb197e..38f087404f7a 100644
--- a/drivers/input/tablet/pegasus_notetaker.c
+++ b/drivers/input/tablet/pegasus_notetaker.c
@@ -275,7 +275,7 @@ static int pegasus_probe(struct usb_interface *intf,
 		return -ENODEV;
 
 	/* Sanity check that the device has an endpoint */
-	if (intf->altsetting[0].desc.bNumEndpoints < 1) {
+	if (intf->cur_altsetting->desc.bNumEndpoints < 1) {
 		dev_err(&intf->dev, "Invalid number of endpoints\n");
 		return -EINVAL;
 	}
-- 
2.24.0