From fbc28a919107bb6fbdceb2d3dfe610ddcbc5ac89 Mon Sep 17 00:00:00 2001
From: fangyufa <fangyufa1@huawei.com>
Date: Tue, 3 Dec 2019 15:42:06 +0800
Subject: [PATCH] zlib: fix undefined buffer detected by oss-fuzz

this patch fixes a use of uninitialized value discovered by one of the
fuzzers of the oss-fuzz project:
https://github.com/google/oss-fuzz/blob/master/projects/zlib/example_dict_fuzzer.c
clear out s->prev buffer to avoid undefined behavior

signed-off-by: fangyufa <fangyufa1@huawei.com>
---
 zlib-1.2.11/deflate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/deflate.c b/deflate.c
index 4c42259..a03bef2 100644
--- a/deflate.c
+++ b/deflate.c
@@ -329,6 +329,7 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
 
     s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
     s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
+    memset(s->prev, 0, s->w_size*sizeof(Pos));
     s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
 
     s->high_water = 0;      /* nothing written to s->window yet */
-- 
2.19.1

