tree f420241fbc3f469085c8d5a2105a90b3fd4d26ac
parent 34ad7cdc1bb2ea65934d235be89fabf1bb40d824
author Heiko Carstens <heiko.carstens@de.ibm.com> 1502111775 +0200
committer Martin Schwidefsky <schwidefsky@de.ibm.com> 1502284172 -0400

s390/vmcp: fix uaccess check and avoid undefined behavior

The vmcp device driver should return -EFAULT if get_user() fails, due
to an invalid user space address. In addition the buffer size value
from user space is passed unchecked to get_order(). The return value
of get_order(0) undefined.

Therefore explicitly test for zero before calling get_order() and also
return -EFAULT if get_user() fails.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>