linux-kernel - Re: [PATCH] signal: remove the wrong signal_pending() check in restore_user

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Message-ID: <CABeXuvp0c+KSimAWPXoV=5GYJGkAfL2s-a71PFZHFDfm4UykzA@mail.gmail.com>
Date:   Tue, 4 Jun 2019 11:14:28 -0700
From:   Deepa Dinamani <deepa.kernel@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dbueso@...e.de, Jens Axboe <axboe@...nel.dk>,
        Davidlohr Bueso <dave@...olabs.net>, Eric Wong <e@...24.org>,
        Jason Baron <jbaron@...mai.com>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
        linux-aio <linux-aio@...ck.org>,
        Omar Kilani <omar.kilani@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "# 3.4.x" <stable@...r.kernel.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Laight <David.Laight@...lab.com>
Subject: Re: [PATCH] signal: remove the wrong signal_pending() check in restore_user_sigmask()

> On Tue, Jun 4, 2019 at 3:41 PM Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > This is the minimal fix for stable, I'll send cleanups later.
> >
> > The commit 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add
> > restore_user_sigmask()") introduced the visible change which breaks
> > user-space: a signal temporary unblocked by set_user_sigmask() can
> > be delivered even if the caller returns success or timeout.
> >
> > Change restore_user_sigmask() to accept the additional "interrupted"
> > argument which should be used instead of signal_pending() check, and
> > update the callers.
> >
> > Reported-by: Eric Wong <e@...24.org>
> > Fixes: 854a6ed56839a40f6b5d02a2962f48841482eec4 ("signal: Add restore_user_sigmask()")
> > cc: stable@...r.kernel.org (v5.0+)
> > Signed-off-by: Oleg Nesterov <oleg@...hat.com>
>

Acked-by: Deepa Dinamani <deepa.kernel@...il.com>

The original fix posted:
https://lore.kernel.org/patchwork/patch/1077355/ would also have been
a correct fix for this problem. But, given the cleanups that are in
the pipeline, this is a better fix.

-Deepa