From: Nick Terrell <terrelln@fb.com>
Date: Tue, 12 May 2020 05:27:34 +0000 (-0700)
Subject: [lib] Fix dictionary + repcodes + optimal parser
X-Git-Tag: v1.4.5^2~17^2~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6d687a88160c50a94cf1dccb0fdbb0b60ea9d936;p=thirdparty%2Fzstd.git

[lib] Fix dictionary + repcodes + optimal parser
---

diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index 890ae9243..36fff050c 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -569,7 +569,10 @@ U32 ZSTD_insertBtAndGetAllMatches (
             U32 repLen = 0;
             assert(current >= dictLimit);
             if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) {  /* equivalent to `current > repIndex >= dictLimit` */
-                if (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch)) {
+                /* We must validate the repcode offset because when we're using a dictionary the
+                 * valid offset range shrinks when the dictionary goes out of bounds.
+                 */
+                if ((repIndex >= windowLow) & (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch))) {
                     repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch;
                 }
             } else {  /* repIndex < dictLimit || repIndex >= current */