From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sadaf Ebrahimi <sadafebrahimi@google.com>
Date: Tue, 22 Nov 2022 22:00:13 +0000
Subject: [PATCH] Fix a bug when getting a gzip header extra field with
 inflate().

If the extra field was larger than the space the user provided with
inflateGetHeader(), and if multiple calls of inflate() delivered
the extra header data, then there could be a buffer overflow of the
provided space. This commit assures that provided space is not
exceeded.

Bug: http://b/242299736
Test: TreeHugger

Change-Id: I4eabb3e135c1568e06b2b9740651a3ae11b21140
---
 src/inflate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/inflate.c b/src/inflate.c
index 4fd3f3c..5c111f5 100644
--- a/src/inflate.c
+++ b/src/inflate.c
@@ -736,8 +736,9 @@ int flush;
                 if (copy > have) copy = have;
                 if (copy) {
                     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_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);
