From: Nathan Moinvaziri <nathan@nathanm.com>
Date: Mon, 4 Jan 2021 05:56:50 +0000 (-0800)
Subject: Add check in check_match for invalid match position.
X-Git-Tag: v2.0.0-RC1~5
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f82f9ea86fa4cdda5038094bda33bc9ba63d3277;p=thirdparty%2Fzlib-ng.git

Add check in check_match for invalid match position.
---

diff --git a/deflate.c b/deflate.c
index 0d1d80c7..f85bbb46 100644
--- a/deflate.c
+++ b/deflate.c
@@ -1201,6 +1201,13 @@ void check_match(deflate_state *s, Pos start, Pos match, int length) {
         fprintf(stderr, " start %u, match %u, length %d\n", start, match, length);
         z_error("invalid match length");
     }
+    /* check that the match isn't at the beginning of the window and that it isn't at
+     * the same position as the start string
+     */
+    if (match == 0 || match == start) {
+        fprintf(stderr, " start %u, match %u, length %d\n", start, match, length);
+        z_error("invalid match position");
+    }
     /* check that the match is indeed a match */
     if (memcmp(s->window + match, s->window + start, length) != EQUAL) {
         int32_t i = 0;