Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756421AbbBFMaq (ORCPT ); Fri, 6 Feb 2015 07:30:46 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:41033 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755332AbbBFMCI (ORCPT ); Fri, 6 Feb 2015 07:02:08 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Andy Lutomirski , torvalds@linux-foundation.org, Thomas Gleixner , Luis Henriques Subject: [PATCH 3.16.y-ckt 050/135] x86, tls, ldt: Stop checking lm in LDT_empty Date: Fri, 6 Feb 2015 12:00:28 +0000 Message-Id: <1423224113-10958-51-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1423224113-10958-1-git-send-email-luis.henriques@canonical.com> References: <1423224113-10958-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2172 Lines: 60 3.16.7-ckt6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski commit e30ab185c490e9a9381385529e0fd32f0a399495 upstream. 32-bit programs don't have an lm bit in their ABI, so they can't reliably cause LDT_empty to return true without resorting to memset. They shouldn't need to do this. This should fix a longstanding, if minor, issue in all 64-bit kernels as well as a potential regression in the TLS hardening code. Fixes: 41bdc78544b8 x86/tls: Validate TLS entries to protect espfix Signed-off-by: Andy Lutomirski Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/72a059de55e86ad5e2935c80aa91880ddf19d07c.1421954363.git.luto@amacapital.net Signed-off-by: Thomas Gleixner Signed-off-by: Luis Henriques --- arch/x86/include/asm/desc.h | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h index 50d033a8947d..fc237fd0259a 100644 --- a/arch/x86/include/asm/desc.h +++ b/arch/x86/include/asm/desc.h @@ -251,7 +251,8 @@ static inline void native_load_tls(struct thread_struct *t, unsigned int cpu) gdt[GDT_ENTRY_TLS_MIN + i] = t->tls_array[i]; } -#define _LDT_empty(info) \ +/* This intentionally ignores lm, since 32-bit apps don't have that field. */ +#define LDT_empty(info) \ ((info)->base_addr == 0 && \ (info)->limit == 0 && \ (info)->contents == 0 && \ @@ -261,12 +262,6 @@ static inline void native_load_tls(struct thread_struct *t, unsigned int cpu) (info)->seg_not_present == 1 && \ (info)->useable == 0) -#ifdef CONFIG_X86_64 -#define LDT_empty(info) (_LDT_empty(info) && ((info)->lm == 0)) -#else -#define LDT_empty(info) (_LDT_empty(info)) -#endif - static inline void clear_LDT(void) { set_ldt(NULL, 0); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/