From b15cf9dfa47ea7868dff1a1bd9579a4e9a0af475 Mon Sep 17 00:00:00 2001
From: Phuc-Thanh Nguyen <83806633+npt-1707@users.noreply.github.com>
Date: Mon, 28 Apr 2025 17:17:58 +0800
Subject: [PATCH] Fix a bug when getting a gzip header extra field with
 inflate() (#2471)

---
 extern/zlib/inflate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/extern/zlib/inflate.c b/extern/zlib/inflate.c
index ac333e8c2..d758a1cc8 100644
--- a/extern/zlib/inflate.c
+++ b/extern/zlib/inflate.c
@@ -758,9 +758,10 @@ int flush;
                 copy = state->length;
                 if (copy > have) copy = have;
                 if (copy) {
+                    len = state->head->extra_len - state->length;
                     if (state->head != Z_NULL &&
-                        state->head->extra != Z_NULL) {
-                        len = state->head->extra_len - state->length;
+                        state->head->extra != Z_NULL &&
+                        len < state->head->extra_max) {
                         zmemcpy(state->head->extra + len, next,
                                 len + copy > state->head->extra_max ?
                                 state->head->extra_max - len : copy);