FRF.16: Add a length check before the bounds check

At the beginning of mfr_print() check the declared length. Updated from e5ae1fd in 4.9 branch.
the-tcpdump-group · Oct 28, 2019 · 4900c02 · 4900c02
1 parent 7ade781
commit 4900c02
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/print-fr.c b/print-fr.c
@@ -458,7 +458,13 @@ mfr_print(netdissect_options *ndo,
  */
 
     ndo->ndo_protocol = "mfr";
-    ND_TCHECK_4(p); /* minimum frame header length */
+
+    if (length < 4) {	/* minimum frame header length */
+        ND_PRINT("[length %u < 4]", length);
+        nd_print_invalid(ndo);
+        return length;
+    }
+    ND_TCHECK_4(p);
 
     if ((GET_U_1(p) & MFR_BEC_MASK) == MFR_CTRL_FRAME && GET_U_1(p + 1) == 0) {
         ND_PRINT("FRF.16 Control, Flags [%s], %s, length %u",