From a014cecd82b71b70a6a843e250e06b541ad524f7 Mon Sep 17 00:00:00 2001 From: Florian Weimer 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 --- 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 @@ -600,9 +600,6 @@ 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)