[PATCH 3.16 081/245] staging: gigaset: fix general protection fault on probe

[Ben Hutchings]

3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

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@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 07dc1f9f2f80 ("[PATCH] isdn4linux: Siemens Gigaset drivers - M105 USB DECT adapter")
Cc: Hansjoerg Lipp <hjlipp@xxxxxx>
Cc: Tilman Schmidt <tilman@xxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20191202085610.12719-2-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/isdn/gigaset/usb-gigaset.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/isdn/gigaset/usb-gigaset.c
+++ b/drivers/isdn/gigaset/usb-gigaset.c
@@ -693,6 +693,11 @@ static int gigaset_probe(struct usb_inte
 		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 */