s390x: sclp: boundary check

All sclp codes need to be checked for page boundary violations.
Signed-off-by: NJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: NJason J. Herne <jjherne@linux.ibm.com>
Message-Id: <1569591203-15258-3-git-send-email-imbrenda@linux.ibm.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

hw/s390x/sclp.c

@@ -234,6 +234,11 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code)
         goto out_write;
     }
 
+    if ((sccb + be16_to_cpu(work_sccb.h.length)) > ((sccb & PAGE_MASK) + PAGE_SIZE)) {
+        work_sccb.h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
+        goto out_write;
+    }
+
     sclp_c->execute(sclp, &work_sccb, code);
 out_write:
     cpu_physical_memory_write(sccb, &work_sccb,