From: Ivan Maidanski <ivmai@mail.ru>
Date: Tue, 19 Jul 2016 22:04:17 +0000 (+0300)
Subject: Fix integer shift undefined behavior in GC_init_explicit_typing
X-Git-Tag: v7.4.6~265
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=5c90e02e6e556b5fd18c63a91595cf65fb6b3652;p=gc

Fix integer shift undefined behavior in GC_init_explicit_typing

* typd_mlc.c (GC_init_explicit_typing): Avoid left-shift by WORDSZ
(which is an undefined behavior), initialize GC_bm_table[0] to
GC_DS_BITMAP explicitly.
---

diff --git a/typd_mlc.c b/typd_mlc.c
index aba9f46c..fde08505 100644
--- a/typd_mlc.c
+++ b/typd_mlc.c
@@ -374,7 +374,8 @@ STATIC void GC_init_explicit_typing(void)
                             (void **)GC_arobjfreelist,
                             GC_MAKE_PROC(GC_array_mark_proc_index, 0),
                             FALSE, TRUE);
-      for (i = 0; i < WORDSZ/2; i++) {
+      GC_bm_table[0] = GC_DS_BITMAP;
+      for (i = 1; i < WORDSZ/2; i++) {
           GC_bm_table[i] = (((word)-1) << (WORDSZ - i)) | GC_DS_BITMAP;
       }
 }