From 49a8fd61c4f8db9b8e9a50e70114cedc5842178e Mon Sep 17 00:00:00 2001
From: starlet-dx <15929766099@163.com>
Date: Tue, 16 May 2023 15:17:40 +0800
Subject: [PATCH 1/1] Fix extra field processing bug that dereferences NULL
 state->head.

The recent commit to fix a gzip header extra field processing bug
introduced the new bug fixed here.
---
 extra/zlib/zlib-1.2.12/inflate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/extra/zlib/zlib-1.2.12/inflate.c b/extra/zlib/zlib-1.2.12/inflate.c
index 7a728974..2a3c4fe9 100644
--- a/extra/zlib/zlib-1.2.12/inflate.c
+++ b/extra/zlib/zlib-1.2.12/inflate.c
@@ -763,10 +763,10 @@ 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_max) {
+                        (len = state->head->extra_len - state->length) <
+                            state->head->extra_max) {
                         zmemcpy(state->head->extra + len, next,
                                 len + copy > state->head->extra_max ?
                                 state->head->extra_max - len : copy);
-- 
2.30.0