staging: gigaset: fix general protection fault on probe

commit 53f35a39c3860baac1e5ca80bf052751cfb24a99 upstream.

Fix a general protection fault when accessing the endpoint descriptors
which could be triggered by a malicious device due to missing sanity
checks on the number of endpoints.

Reported-by: syzbot+35b1c403a14f5c89eba7@syzkaller.appspotmail.com
Fixes: 07dc1f9f2f80 ("[PATCH] isdn4linux: Siemens Gigaset drivers - M105 USB DECT adapter")
Cc: Hansjoerg Lipp <hjlipp@web.de>
Cc: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191202085610.12719-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/isdn/gigaset/usb-gigaset.c b/drivers/isdn/gigaset/usb-gigaset.c
index d0a41cb0cf627fe8c6687324e93f9dd3cb0384b7..648355d0b67f45c9471d78118288f241262002c0 100644 (file)
--- a/drivers/isdn/gigaset/usb-gigaset.c
+++ b/drivers/isdn/gigaset/usb-gigaset.c
@@ -693,6 +693,11 @@ static int gigaset_probe(struct usb_interface *interface,
                return -ENODEV;
        }
 
+       if (hostif->desc.bNumEndpoints < 2) {
+               dev_err(&interface->dev, "missing endpoints\n");
+               return -ENODEV;
+       }
+
        dev_info(&udev->dev, "%s: Device matched ... !\n", __func__);
 
        /* allocate memory for our device state and initialize it */