1 files changed, 14 insertions, 12 deletions

diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
index 4ae6fb400b..0d54075309 100644
--- a/hw/s390x/sclp.c
+++ b/hw/s390x/sclp.c
@@ -78,6 +78,8 @@ static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int *count)
     }
 }
 
+#define SCCB_REQ_LEN(s, max_cpus) (sizeof(s) + max_cpus * sizeof(CPUEntry))
+
 /* Provide information about the configuration, CPUs and storage */
 static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
 {
@@ -86,6 +88,12 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
     int cpu_count;
     int rnsize, rnmax;
     IplParameterBlock *ipib = s390_ipl_get_iplb();
+    int required_len = SCCB_REQ_LEN(ReadInfo, machine->possible_cpus->len);
+
+    if (be16_to_cpu(sccb->h.length) < required_len) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+        return;
+    }
 
     /* CPU information */
     prepare_cpu_entries(machine, read_info->entries, &cpu_count);
@@ -95,12 +103,6 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
 
     read_info->ibc_val = cpu_to_be32(s390_get_ibc_val());
 
-    if (be16_to_cpu(sccb->h.length) <
-            (sizeof(ReadInfo) + cpu_count * sizeof(CPUEntry))) {
-        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
-        return;
-    }
-
     /* Configuration Characteristic (Extension) */
     s390_get_feat_block(S390_FEAT_TYPE_SCLP_CONF_CHAR,
                          read_info->conf_char);
@@ -146,18 +148,18 @@ static void sclp_read_cpu_info(SCLPDevice *sclp, SCCB *sccb)
     MachineState *machine = MACHINE(qdev_get_machine());
     ReadCpuInfo *cpu_info = (ReadCpuInfo *) sccb;
     int cpu_count;
+    int required_len = SCCB_REQ_LEN(ReadCpuInfo, machine->possible_cpus->len);
+
+    if (be16_to_cpu(sccb->h.length) < required_len) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+        return;
+    }
 
     prepare_cpu_entries(machine, cpu_info->entries, &cpu_count);
     cpu_info->nr_configured = cpu_to_be16(cpu_count);
     cpu_info->offset_configured = cpu_to_be16(offsetof(ReadCpuInfo, entries));
     cpu_info->nr_standby = cpu_to_be16(0);
 
-    if (be16_to_cpu(sccb->h.length) <
-            (sizeof(ReadCpuInfo) + cpu_count * sizeof(CPUEntry))) {
-        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
-        return;
-    }
-
     /* The standby offset is 16-byte for each CPU */
     cpu_info->offset_standby = cpu_to_be16(cpu_info->offset_configured
         + cpu_info->nr_configured*sizeof(CPUEntry));