From 431a9b65eacab7efabf2230ba97ff426c0e07f9d Mon Sep 17 00:00:00 2001
From: Mark Adler <madler@alumni.caltech.edu>
Date: Thu, 7 Dec 2023 06:38:10 -0800
Subject: [PATCH] Add bounds checking to ERR_MSG() macro, used by zError().

---
 zutil.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/zutil.h b/zutil.h
index 902a304cc..0bd2dbcba 100644
--- a/zutil.h
+++ b/zutil.h
@@ -56,7 +56,7 @@ typedef unsigned long  ulg;
 extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
 /* (size given to avoid silly warnings with Visual C++) */
 
-#define ERR_MSG(err) z_errmsg[Z_NEED_DICT-(err)]
+#define ERR_MSG(err) z_errmsg[(err) < -6 || (err) > 2 ? 9 : 2 - (err)]
 
 #define ERR_RETURN(strm,err) \
   return (strm->msg = ERR_MSG(err), (err))