From: Yann Collet <cyan@fb.com>
Date: Tue, 18 Oct 2016 00:28:28 +0000 (-0700)
Subject: fixed minor corner case
X-Git-Tag: v1.1.1~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=06573e17be39c6f308fc09a40efab58773902a3e;p=thirdparty%2Fzstd.git

fixed minor corner case
---

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 990a64910..00b069e9f 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -807,7 +807,8 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
         if (ofCode <= 1) {
             offset += (llCode==0);
             if (offset) {
-                size_t const temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
+                size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
+                temp += !temp;   /* 0 is not valid; input is corrupted; force offset to 1 */
                 if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
                 seqState->prevOffset[1] = seqState->prevOffset[0];
                 seqState->prevOffset[0] = offset = temp;