linux-kernel - Re: [RESEND PATCH] ptrace: take into account saved_sigmask in PTRACE

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Message-Id: <20190319155804.277fec5dba6a93ad2ab3edbc@linux-foundation.org>
Date:   Tue, 19 Mar 2019 15:58:04 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     "Dmitry V. Levin" <ldv@...linux.org>
Cc:     Andrei Vagin <avagin@...il.com>, Oleg Nesterov <oleg@...hat.com>,
        linux-kernel@...r.kernel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [RESEND PATCH] ptrace: take into account saved_sigmask in
 PTRACE_{GET,SET}SIGMASK

On Wed, 20 Mar 2019 01:32:53 +0300 "Dmitry V. Levin" <ldv@...linux.org> wrote:

> On Tue, Mar 19, 2019 at 12:19:57PM -0700, Andrei Vagin wrote:
> > There are a few system calls (pselect, ppoll, etc) which replace a task
> > sigmask while they are running in a kernel-space
> > 
> > When a task calls one of these syscalls, the kernel saves a current
> > sigmask in task->saved_sigmask and sets a syscall sigmask.
> > 
> > On syscall-exit-stop, ptrace traps a task before restoring the
> > saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and
> > PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by
> > saved_sigmask, when the task returns to user-space.
> > 
> > This patch fixes this problem.  PTRACE_GET_SIGMASK returns saved_sigmask
> > is it's set.  PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag.
> 
> If it's not too late, could somebody tweak the commit message so that
> PTRACE_GET_SIGMASK becomes PTRACE_GETSIGMASK and "is it's set" is changed
> to "if it's set", please?

I made those changes to my copy.