diff mbox series

[v6,4/8] s390/sclp: check sccb len before filling in data

Message ID 20200915194416.107460-5-walling@linux.ibm.com
State New
Headers show
Series s390: Extended-Length SCCB & DIAGNOSE 0x318 | expand

Commit Message

Collin Walling Sept. 15, 2020, 7:44 p.m. UTC 
The SCCB must be checked for a sufficient length before it is filled
with any data. If the length is insufficient, then the SCLP command
is suppressed and the proper response code is set in the SCCB header.

While we're at it, let's cleanup the length check by placing the
calculation inside a macro.

Fixes: 832be0d8a3bb ("s390x: sclp: Report insufficient SCCB length")
Signed-off-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 hw/s390x/sclp.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)
diff mbox series

Patch

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));