zlib: backport null dereference fix

The curl developers found test case that crashed in their testing when
using zlib patched against CVE-2022-37434, same patch we've backported
in commit 7df6795d4c25 ("zlib: backport fix for heap-based buffer
over-read (CVE-2022-37434)"). So we need to backport following patch in
order to fix issue introduced in that previous CVE-2022-37434 fix.

References: curl/curl#9271
Fixes: 7df6795d4c25 ("zlib: backport fix for heap-based buffer over-read (CVE-2022-37434)")
Signed-off-by: Petr Štetiar <ynezz@true.cz>

package/libs/zlib/patches/007-fix-null-dereference-in-fix-CVE-2022-37434.patch

@@ -0,0 +1,29 @@
+From 1eb7682f845ac9e9bf9ae35bbfb3bad5dacbd91d Mon Sep 17 00:00:00 2001
+From: Mark Adler <fork@madler.net>
+Date: Mon, 8 Aug 2022 10:50:09 -0700
+Subject: [PATCH] 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.
+---
+ inflate.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/inflate.c b/inflate.c
+index 7a7289749..2a3c4fe98 100644
+--- a/inflate.c
++++ b/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);