linux-kernel - Re: [PATCH 3/6] exec: Stop open coding mutex_lock_killable of cred_guard

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Message-ID: <202005082208.5FB101297A@keescook>
Date:   Fri, 8 May 2020 22:08:24 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>, Jann Horn <jannh@...gle.com>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Rob Landley <rob@...dley.net>,
        Bernd Edlinger <bernd.edlinger@...mail.de>,
        linux-fsdevel@...r.kernel.org, Al Viro <viro@...IV.linux.org.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 3/6] exec: Stop open coding mutex_lock_killable of
 cred_guard_mutex

On Fri, May 08, 2020 at 01:45:25PM -0500, Eric W. Biederman wrote:
> 
> Oleg modified the code that did
> "mutex_lock_interruptible(&current->cred_guard_mutex)" to return
> -ERESTARTNOINTR instead of -EINTR, so that userspace will never see a
> failure to grab the mutex.
> 
> Slightly earlier Liam R. Howlett defined mutex_lock_killable for
> exactly the same situation but it does it a little more cleanly.
> 
> Switch the code to mutex_lock_killable so that it is clearer what the
> code is doing.
> 
> Ref: ad776537cc6b ("Add mutex_lock_killable")
> Ref: 793285fcafce ("cred_guard_mutex: do not return -EINTR to user-space")
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook