From 6c35fb2e8cb826b70226856cd7442861037cca8a Mon Sep 17 00:00:00 2001
From: Yann Collet <yann.collet.73@gmail.com>
Date: Mon, 5 Feb 2024 01:21:06 -0800
Subject: [PATCH] fix msan warnings

---
 Makefile                |  5 +++--
 lib/compress/zstd_opt.c | 14 ++++++++++----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 87d80d16d..11eca19ce 100644
--- a/Makefile
+++ b/Makefile
@@ -328,8 +328,9 @@ asan-%: clean
 msan: clean
 	$(MAKE) test CC=clang MOREFLAGS="-g -fsanitize=memory -fno-omit-frame-pointer -Werror $(MOREFLAGS)" HAVE_LZMA=0   # datagen.c fails this test for no obvious reason
 
-msan-%: clean
-	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=memory -fno-omit-frame-pointer -Werror $(MOREFLAGS)" FUZZER_FLAGS="--no-big-tests $(FUZZER_FLAGS)" $(MAKE) -C $(TESTDIR) HAVE_LZMA=0 $*
+msan-%:
+	$(MAKE) clean
+	LDFLAGS=-fuse-ld=gold MOREFLAGS="-g -fno-sanitize-recover=all -fsanitize=memory -fno-omit-frame-pointer -Werror $(MOREFLAGS)" FUZZER_FLAGS="--no-big-tests $(FUZZER_FLAGS)" $(MAKE) -j -C $(TESTDIR) HAVE_LZMA=0 $*
 
 asan32: clean
 	$(MAKE) -C $(TESTDIR) test32 CC=clang MOREFLAGS="-g -fsanitize=address $(MOREFLAGS)"
diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index eed331929..25715eabb 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -1164,7 +1164,8 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
                 U32 matchNb;
                 for (pos = 1; pos < minMatch; pos++) {
                     opt[pos].price = ZSTD_MAX_PRICE;
-                    /* will be updated later on at match check */
+                    opt[pos].mlen = 0;
+                    opt[pos].litlen = litlen + pos;
                 }
                 for (matchNb = 0; matchNb < nbMatches; matchNb++) {
                     U32 const offBase = matches[matchNb].off;
@@ -1205,8 +1206,8 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
                     opt[cur] = opt[cur-1];
                     opt[cur].litlen = litlen;
                     opt[cur].price = price;
-                    if ( (optLevel == 2) /* additional check only for high modes */
-                      && (prevMatch.litlen == 0) /* interrupt a match */
+                    if ( (optLevel >= 1) /* additional check only for higher modes */
+                      && (prevMatch.litlen == 0) /* replace a match */
                       && (LL_INCPRICE(1) < 0) /* ll1 is cheaper than ll0 */
                     ) {
                         /* check next position, in case it would be cheaper */
@@ -1305,7 +1306,12 @@ ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms,
                         if ((pos > last_pos) || (price < opt[pos].price)) {
                             DEBUGLOG(7, "rPos:%u (ml=%2u) => new better price (%.2f<%.2f)",
                                         pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price));
-                            while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; }   /* fill empty positions */
+                            while (last_pos < pos) {
+                                /* fill empty positions, for future comparisons */
+                                last_pos++;
+                                opt[last_pos].price = ZSTD_MAX_PRICE;
+                                opt[last_pos].litlen = !0;  /* just needs to be != 0, to mean "not an end of match" */
+                            }
                             opt[pos].mlen = mlen;
                             opt[pos].off = offset;
                             opt[pos].litlen = 0;
-- 
2.47.2