10145 smbios_info_boot() gets NULL check wrong

@@ -19,11 +19,11 @@
  * CDDL HEADER END
  */
 
 /*
  * Copyright 2015 OmniTI Computer Consulting, Inc.  All rights reserved.
- * Copyright (c) 2017, Joyent, Inc.
+ * Copyright (c) 2018, Joyent, Inc.
  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
 /*

@@ -981,17 +981,19 @@
 
 id_t
 smbios_info_boot(smbios_hdl_t *shp, smbios_boot_t *bp)
 {
         const smb_struct_t *stp = smb_lookup_type(shp, SMB_TYPE_BOOT);
-        const smb_boot_t *b = (smb_boot_t *)(uintptr_t)stp->smbst_hdr;
+        const smb_boot_t *b;
 
         if (stp == NULL)
                 return (-1); /* errno is set for us */
 
         bzero(bp, sizeof (smbios_boot_t));
 
+        b = (smb_boot_t *)(uintptr_t)stp->smbst_hdr;
+
         bp->smbt_status = b->smbbo_status[0];
         bp->smbt_size = stp->smbst_hdr->smbh_len - sizeof (smb_boot_t);
         bp->smbt_data = bp->smbt_size ? &b->smbbo_status[1] : NULL;
 
         return (stp->smbst_hdr->smbh_hdl);