[v2.6.34-stable 150/213] USB: CDC ACM: Fix NULL pointer dereference

[Paul Gortmaker]

From: Sven Schnelle <svens@xxxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/usb/class/cdc-acm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index af45f735f6e5..45f85df306e5 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1120,7 +1120,8 @@ 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;
-- 
1.8.5.2

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