glibc: CVE-2015-8777

The process_envvars function in elf/rtld.c in the GNU C Library (aka glibc or
libc6) before 2.23 allows local users to bypass a pointer-guarding protection
mechanism via a zero value of the LD_POINTER_GUARD environment variable.

(From OE-Core rev: 22570ba08d7c6157aec58764c73b1134405b0252)

(From OE-Core rev: 9cc998978bd67bc5569cc1478f4ddee40020b929)

Signed-off-by: Armin Kuster <akuster@mvista.com>
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster@mvista.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 123 insertions, 0 deletions

diff --git a/meta/recipes-core/glibc/glibc/CVE-2015-8777.patch b/meta/recipes-core/glibc/glibc/CVE-2015-8777.patch
new file mode 100644
index 0000000000..9b9ab3bade
--- /dev/null
+++ b/meta/recipes-core/glibc/glibc/CVE-2015-8777.patch
@@ -0,0 +1,122 @@
+From a014cecd82b71b70a6a843e250e06b541ad524f7 Mon Sep 17 00:00:00 2001
+From: Florian Weimer <fweimer@redhat.com>
+Date: Thu, 15 Oct 2015 09:23:07 +0200
+Subject: [PATCH] Always enable pointer guard [BZ #18928]
+
+Honoring the LD_POINTER_GUARD environment variable in AT_SECURE mode
+has security implications.  This commit enables pointer guard
+unconditionally, and the environment variable is now ignored.
+
+        [BZ #18928]
+        * sysdeps/generic/ldsodefs.h (struct rtld_global_ro): Remove
+        _dl_pointer_guard member.
+        * elf/rtld.c (_rtld_global_ro): Remove _dl_pointer_guard
+        initializer.
+        (security_init): Always set up pointer guard.
+        (process_envvars): Do not process LD_POINTER_GUARD.
+
+Upstream-Status: Backport
+CVE: CVE-2015-8777
+[Yocto # 8980]
+
+https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commit;h=a014cecd82b71b70a6a843e250e06b541ad524f7
+
+Signed-off-by: Armin Kuster <akuster@mvista.com>
+
+---
+ ChangeLog                  | 10 ++++++++++
+ NEWS                       | 13 ++++++++-----
+ elf/rtld.c                 | 15 ++++-----------
+ sysdeps/generic/ldsodefs.h |  3 ---
+ 4 files changed, 22 insertions(+), 19 deletions(-)
+
+Index: git/elf/rtld.c
+===================================================================
+--- git.orig/elf/rtld.c
++++ git/elf/rtld.c
+@@ -163,7 +163,6 @@ struct rtld_global_ro _rtld_global_ro at
+     ._dl_hwcap_mask = HWCAP_IMPORTANT,
+     ._dl_lazy = 1,
+     ._dl_fpu_control = _FPU_DEFAULT,
+-    ._dl_pointer_guard = 1,
+     ._dl_pagesize = EXEC_PAGESIZE,
+     ._dl_inhibit_cache = 0,
+ 
+@@ -710,15 +709,12 @@ security_init (void)
+ #endif
+ 
+   /* Set up the pointer guard as well, if necessary.  */
+-  if (GLRO(dl_pointer_guard))
+-    {
+-      uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random,
+-                                                            stack_chk_guard);
++  uintptr_t pointer_chk_guard
++    = _dl_setup_pointer_guard (_dl_random, stack_chk_guard);
+ #ifdef THREAD_SET_POINTER_GUARD
+-      THREAD_SET_POINTER_GUARD (pointer_chk_guard);
++  THREAD_SET_POINTER_GUARD (pointer_chk_guard);
+ #endif
+-      __pointer_chk_guard_local = pointer_chk_guard;
+-    }
++  __pointer_chk_guard_local = pointer_chk_guard;
+ 
+   /* We do not need the _dl_random value anymore.  The less
+      information we leave behind, the better, so clear the
+@@ -2478,9 +2474,6 @@ process_envvars (enum mode *modep)
+              GLRO(dl_use_load_bias) = envline[14] == '1' ? -1 : 0;
+              break;
+            }
+-
+-         if (memcmp (envline, "POINTER_GUARD", 13) == 0)
+-           GLRO(dl_pointer_guard) = envline[14] != '0';
+          break;
+ 
+        case 14:
+Index: git/sysdeps/generic/ldsodefs.h
+===================================================================
+--- git.orig/sysdeps/generic/ldsodefs.h
++++ git/sysdeps/generic/ldsodefs.h
+@@ -590,9 +590,6 @@ struct rtld_global_ro
+   /* List of auditing interfaces.  */
+   struct audit_ifaces *_dl_audit;
+   unsigned int _dl_naudit;
+-
+-  /* 0 if internal pointer values should not be guarded, 1 if they should.  */
+-  EXTERN int _dl_pointer_guard;
+ };
+ # define __rtld_global_attribute__
+ # if IS_IN (rtld)
+Index: git/ChangeLog
+===================================================================
+--- git.orig/ChangeLog
++++ git/ChangeLog
+@@ -1,3 +1,13 @@
++2015-10-15  Florian Weimer  <fweimer@redhat.com>
++
++   [BZ #18928]
++   * sysdeps/generic/ldsodefs.h (struct rtld_global_ro): Remove
++   _dl_pointer_guard member.
++   * elf/rtld.c (_rtld_global_ro): Remove _dl_pointer_guard
++   initializer.
++   (security_init): Always set up pointer guard.
++   (process_envvars): Do not process LD_POINTER_GUARD.
++
+ 2015-02-06  Carlos O'Donell  <carlos@systemhalted.org>
+ 
+        * version.h (RELEASE): Set to "stable".
+Index: git/NEWS
+===================================================================
+--- git.orig/NEWS
++++ git/NEWS
+@@ -19,7 +19,10 @@ Version 2.21
+   17722, 17723, 17724, 17725, 17732, 17733, 17744, 17745, 17746, 17747,
+   17748, 17775, 17777, 17780, 17781, 17782, 17791, 17793, 17796, 17797,
+   17801, 17803, 17806, 17834, 17844, 17848, 17868, 17869, 17870, 17885,
+-  17892.
++  17892, 18928.
++
++* The LD_POINTER_GUARD environment variable can no longer be used to
++  disable the pointer guard feature.  It is always enabled.
+ 
+ * CVE-2015-1472 Under certain conditions wscanf can allocate too little
+   memory for the to-be-scanned arguments and overflow the allocated
diff --git a/meta/recipes-core/glibc/glibc_2.21.bb b/meta/recipes-core/glibc/glibc_2.21.bb
index 3bba7346f9..efbcc9c51e 100644
--- a/meta/recipes-core/glibc/glibc_2.21.bb
+++ b/meta/recipes-core/glibc/glibc_2.21.bb
@@ -48,6 +48,7 @@ EGLIBCPATCHES = "\
 #
 CVEPATCHES = "\
         file://CVE-2015-1781-resolv-nss_dns-dns-host.c-buffer-overf.patch \
+        file://CVE-2015-8777.patch \
 "
 
 LIC_FILES_CHKSUM = "file://LICENSES;md5=e9a558e243b36d3209f380deb394b213 \