[ 50/95] USB: CDC ACM: Fix NULL pointer dereference

From: Ben Hutchings
Date: Sun Sep 09 2012 - 19:24:51 EST

3.2-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>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
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 56d6bf6..f763ed7 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1104,7 +1104,8 @@ 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;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/