From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932667Ab0EXXXy (ORCPT ); Mon, 24 May 2010 19:23:54 -0400 Received: from kroah.org ([198.145.64.141]:59384 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932406Ab0EXXXh (ORCPT ); Mon, 24 May 2010 19:23:37 -0400 X-Mailbox-Line: From gregkh@clark.site Mon May 24 16:18:14 2010 Message-Id: <20100524231814.547878097@clark.site> User-Agent: quilt/0.48-8.10 Date: Mon, 24 May 2010 16:15:27 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Gerald Schaefer , Martin Schwidefsky Subject: [15/39] [S390] ptrace: fix return value of do_syscall_trace_enter() In-Reply-To: <20100524231840.GA17857@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Gerald Schaefer commit 545c174d1f093a462b4bb9131b23d5ea72a600e1 upstream. strace may change the system call number, so regs->gprs[2] must not be read before tracehook_report_syscall_entry(). This fixes a bug where "strace -f" will hang after a vfork(). Signed-off-by: Gerald Schaefer Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/ptrace.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/arch/s390/kernel/ptrace.c +++ b/arch/s390/kernel/ptrace.c @@ -640,7 +640,7 @@ long compat_arch_ptrace(struct task_stru asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) { - long ret; + long ret = 0; /* Do the secure computing check first. */ secure_computing(regs->gprs[2]); @@ -649,7 +649,6 @@ asmlinkage long do_syscall_trace_enter(s * The sysc_tracesys code in entry.S stored the system * call number to gprs[2]. */ - ret = regs->gprs[2]; if (test_thread_flag(TIF_SYSCALL_TRACE) && (tracehook_report_syscall_entry(regs) || regs->gprs[2] >= NR_syscalls)) { @@ -671,7 +670,7 @@ asmlinkage long do_syscall_trace_enter(s regs->gprs[2], regs->orig_gpr2, regs->gprs[3], regs->gprs[4], regs->gprs[5]); - return ret; + return ret ?: regs->gprs[2]; } asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)