From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + ptrace-clear-tif_syscall_trace-on-ptrace-detach.patch added to -mm tree Date: Thu, 01 Sep 2016 15:02:53 -0700 Message-ID: <57c8a58d.2KKB2IPfLIn4FSAR%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59496 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752353AbcIAWCy (ORCPT ); Thu, 1 Sep 2016 18:02:54 -0400 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: alnovak@suse.cz, jkosina@suse.cz, oleg@redhat.com, mm-commits@vger.kernel.org The patch titled Subject: ptrace: clear TIF_SYSCALL_TRACE on ptrace detach has been added to the -mm tree. Its filename is ptrace-clear-tif_syscall_trace-on-ptrace-detach.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/ptrace-clear-tif_syscall_trace-on-ptrace-detach.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/ptrace-clear-tif_syscall_trace-on-ptrace-detach.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Ales Novak Subject: ptrace: clear TIF_SYSCALL_TRACE on ptrace detach On __ptrace_detach(), called from do_exit()->exit_notify()-> forget_original_parent()->exit_ptrace(), the TIF_SYSCALL_TRACE in thread->flags of the tracee is not cleared up. This results in the tracehook_report_syscall_* being called (though there's no longer a tracer listening to that) upon its further syscalls. Example scenario - attach "strace" to a running process and kill it (the strace) with SIGKILL. You'll see that the syscall trace hooks are still being called. The clearing of this flag should be moved from ptrace_detach() to __ptrace_detach(). Link: http://lkml.kernel.org/r/1472759493-20554-1-git-send-email-alnovak@suse.cz Signed-off-by: Ales Novak Cc: Jiri Kosina Cc: Oleg Nesterov Signed-off-by: Andrew Morton --- kernel/ptrace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN kernel/ptrace.c~ptrace-clear-tif_syscall_trace-on-ptrace-detach kernel/ptrace.c --- a/kernel/ptrace.c~ptrace-clear-tif_syscall_trace-on-ptrace-detach +++ a/kernel/ptrace.c @@ -73,6 +73,8 @@ void __ptrace_unlink(struct task_struct { BUG_ON(!child->ptrace); + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + child->parent = child->real_parent; list_del_init(&child->ptrace_entry); @@ -489,7 +491,6 @@ static int ptrace_detach(struct task_str /* Architecture-specific hardware disable .. */ ptrace_disable(child); - clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); write_lock_irq(&tasklist_lock); /* _ Patches currently in -mm which might be from alnovak@suse.cz are ptrace-clear-tif_syscall_trace-on-ptrace-detach.patch