[ 32/46] USB: CDC ACM: Fix NULL pointer dereference

[Greg Kroah-Hartman]

From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

3.0-stable review patch.  If anyone has any objections, please let me know.

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

From: Sven Schnelle <svens@xxxxxxxxxxxxxx>

commit 99f347caa4568cb803862730b3b1f1942639523f upstream.

If a device specifies zero endpoints in its interface descriptor,
the kernel oopses in acm_probe(). Even though that's clearly an
invalid descriptor, we should test wether we have all endpoints.
This is especially bad as this oops can be triggered by just
plugging a USB device in.

Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/class/cdc-acm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1043,7 +1043,8 @@ skip_normal_probe:
 	}
 
 
-	if (data_interface->cur_altsetting->desc.bNumEndpoints < 2)
+	if (data_interface->cur_altsetting->desc.bNumEndpoints < 2 ||
+	    control_interface->cur_altsetting->desc.bNumEndpoints == 0)
 		return -EINVAL;
 
 	epctrl = &control_interface->cur_altsetting->endpoint[0].desc;


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