Before reading data in os_info_get(), check the validity of the memory
range. Otherwise this can result in a segmentation fault when zgetdump is
given a very small dump, e.g. S390 DASD single-volume dump of size 0x10
bytes.
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>