From efa26d9c13a6fabd34a05139e1d8b2e441b2fae9 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Mon, 19 Jun 2017 18:34:53 +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)
---
 ChangeLog  | 7 +++++++
 NEWS       | 1 +
 elf/rtld.c | 3 ++-
 3 files changed, 10 insertions(+), 1 deletion(-)

#diff --git a/ChangeLog b/ChangeLog
#index 989e0da9ae..5e5e8615b4 100644
#--- a/ChangeLog
#+++ b/ChangeLog
#@@ -1,3 +1,10 @@
#+2017-06-19  Florian Weimer  <fweimer@redhat.com>
#+
#+	[BZ #21624]
#+	CVE-2017-1000366
#+	* elf/rtld.c (process_envvars): Ignore LD_LIBRARY_PATH for
#+	__libc_enable_secure.
#+
# 2017-03-31  Slava Barinov  <v.barinov@samsung.com>
# 
# 	[BZ #21289]
#diff --git a/NEWS b/NEWS
#index c7ff11610e..76a7f6a193 100644
#--- a/NEWS
#+++ b/NEWS
#@@ -43,6 +43,7 @@ The following bugs are resolved with this release:
#   [20177] $dp is not initialized correctly in sysdeps/hppa/start.S
#   [20357] Incorrect cos result for 1.5174239687223976
#   [21289] Fix symbol redirect for fts_set
#+  [21624] Unsafe alloca allows local attackers to alias stack and heap (CVE-2017-1000366)
# 
# 
# Version 2.23
diff --git a/elf/rtld.c b/elf/rtld.c
index 647661ca45..215a9aec8f 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2437,7 +2437,8 @@ 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;
-- 
2.13.1