From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932743Ab2JAXAr (ORCPT ); Mon, 1 Oct 2012 19:00:47 -0400 Received: from 1wt.eu ([62.212.114.60]:35203 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932643Ab2JAXAk (ORCPT ); Mon, 1 Oct 2012 19:00:40 -0400 Message-Id: <20121001225201.077130761@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 02 Oct 2012 00:53:19 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Tim Bird , Russell King , Greg Kroah-Hartman , Willy Tarreau Subject: [ 082/180] ARM: 7410/1: Add extra clobber registers for assembly in kernel_execve In-Reply-To: <6a854f579a99b4fe2efaca1057e8ae22@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Tim Bird commit e787ec1376e862fcea1bfd523feb7c5fb43ecdb9 upstream. The inline assembly in kernel_execve() uses r8 and r9. Since this code sequence does not return, it usually doesn't matter if the register clobber list is accurate. However, I saw a case where a particular version of gcc used r8 as an intermediate for the value eventually passed to r9. Because r8 is used in the inline assembly, and not mentioned in the clobber list, r9 was set to an incorrect value. This resulted in a kernel panic on execution of the first user-space program in the system. r9 is used in ret_to_user as the thread_info pointer, and if it's wrong, bad things happen. Signed-off-by: Tim Bird Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- arch/arm/kernel/sys_arm.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c index ae4027b..2dd070f 100644 --- a/arch/arm/kernel/sys_arm.c +++ b/arch/arm/kernel/sys_arm.c @@ -240,7 +240,7 @@ int kernel_execve(const char *filename, char *const argv[], char *const envp[]) "Ir" (THREAD_START_SP - sizeof(regs)), "r" (®s), "Ir" (sizeof(regs)) - : "r0", "r1", "r2", "r3", "ip", "lr", "memory"); + : "r0", "r1", "r2", "r3", "r8", "r9", "ip", "lr", "memory"); out: return ret; -- 1.7.2.1.45.g54fbc