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/ChangeLog b/ChangeLog
index 1795e284ef6536259514a68530b76651cb778299..e37f14f02a1d9c61740f8b49a52b5aca79780897 100644 (file)
--- 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.
+
 2017-02-01  Andreas Schwab  <schwab@linux-m68k.org>
 
        * sysdeps/m68k/m680x0/m68020/atomic-machine.h

diff --git a/NEWS b/NEWS
index 82a718ff64ab849ba6929ff9af35b65fb84bbb94..d42af919728485080335f8a5d5a788d5d7994d8c 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -25,6 +25,7 @@ The following bugs are resolved with this release:
 
   [21289] Fix symbol redirect for fts_set
   [21386] Assertion in fork for distinct parent PID is incorrect
+  [21624] Unsafe alloca allows local attackers to alias stack and heap (CVE-2017-1000366)
 \f
 Version 2.24
 

diff --git a/elf/rtld.c b/elf/rtld.c
index 647661ca45901d6e42c3c52475030d8dd06b61ab..215a9aec8f19b6cdd8b5c9b52e5da3cd82c75c12 100644 (file)
--- 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;