ssi-sd: fix buffer overrun on invalid state load

CVE-2013-4537

s->arglen is taken from wire and used as idx
in ssi_sd_transfer().

Validate it before access.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

hw/sd/ssi-sd.c

@@ -230,8 +230,17 @@ static int ssi_sd_load(QEMUFile *f, void *opaque, int version_id)
     for (i = 0; i < 5; i++)
         s->response[i] = qemu_get_be32(f);
     s->arglen = qemu_get_be32(f);
+    if (s->mode == SSI_SD_CMDARG &&
+        (s->arglen < 0 || s->arglen >= ARRAY_SIZE(s->cmdarg))) {
+        return -EINVAL;
+    }
     s->response_pos = qemu_get_be32(f);
     s->stopping = qemu_get_be32(f);
+    if (s->mode == SSI_SD_RESPONSE &&
+        (s->response_pos < 0 || s->response_pos >= ARRAY_SIZE(s->response) ||
+        (!s->stopping && s->arglen > ARRAY_SIZE(s->response)))) {
+        return -EINVAL;
+    }
 
     ss->cs = qemu_get_be32(f);