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Subject[ 50/95] USB: CDC ACM: Fix NULL pointer dereference
3.2-stable review patch.  If anyone has any objections, please let me know.

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

From: Sven Schnelle <svens@stackframe.org>

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@stackframe.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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;



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