From 3c7cd21290cabdadd72984fb69bc51e64ff1002d Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Mon, 19 Jun 2017 18:31:27 +0200
Subject: [PATCH] CVE-2017-1000366: Ignore LD_LIBRARY_PATH for AT_SECURE=1
 programs [BZ #21624]

LD_LIBRARY_PATH can only be used to reorder system search paths, which
is not useful functionality.

This makes an exploitable unbounded alloca in _dl_init_paths unreachable
for AT_SECURE=1 programs.

(cherry picked from commit f6110a8fee2ca36f8e2d2abecf3cba9fa7b8ea7d)
 
diff --git a/elf/rtld.c b/elf/rtld.c
index a036ece..2fc33a6 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2418,7 +2418,8 @@ process_envvars (enum mode *modep)
 
 	case 12:
 	  /* The library search path.  */
-	  if (memcmp (envline, "LIBRARY_PATH", 12) == 0)
+	  if (!__libc_enable_secure
+	      && memcmp (envline, "LIBRARY_PATH", 12) == 0)
 	    {
 	      library_path = &envline[13];
 	      break;
-- 
2.9.3