Fix potential buffer underflow in icom.c

rigs/icom/icom.c

@@ -1824,6 +1824,7 @@ int icom_set_mode_with_data(RIG *rig, vfo_t vfo, rmode_t mode,
         rig_debug(RIG_DEBUG_TRACE, "%s: mode/width not changing\n", __func__);
         RETURNFUNC(RIG_OK);
     }
+
     // looks like we need to change it
 
     switch (mode)
@@ -8494,6 +8495,13 @@ int icom_decode_event(RIG *rig)
 
     frm_len = retval;
 
+    if (frm_len < 1)
+    {
+        rig_debug(RIG_DEBUG_ERR, "Unexpected frame len=%d\n", frm_len);
+        RETURNFUNC(-RIG_EPROTO);
+    }
+
+
     switch (buf[frm_len - 1])
     {
     case COL:

rigs/icom/icom.h

@@ -30,7 +30,7 @@
 #include <sys/time.h>
 #endif
 
-#define BACKEND_VER "20210907"
+#define BACKEND_VER "20210911"
 
 #define ICOM_IS_SECONDARY_VFO(vfo) ((vfo) & (RIG_VFO_B | RIG_VFO_SUB | RIG_VFO_SUB_B | RIG_VFO_MAIN_B))
 #define ICOM_GET_VFO_NUMBER(vfo) (ICOM_IS_SECONDARY_VFO(vfo) ? 0x01 : 0x00)