linux-kernel - Re: [PATCH 2/3] exec: Make unlocking exec_update

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Message-ID: <20200407161706.l5zfgghwr3p4vz2c@wittgenstein>
Date:   Tue, 7 Apr 2020 18:17:06 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Bernd Edlinger <bernd.edlinger@...mail.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Alexey Gladkov <gladkov.alexey@...il.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Kees Cook <keescook@...omium.org>, Jann Horn <jannh@...gle.com>
Subject: Re: [PATCH 2/3] exec: Make unlocking exec_update_mutex explict

On Mon, Apr 06, 2020 at 08:31:52PM -0500, Eric W. Biederman wrote:
> 
> With install_exec_creds updated to follow immediately after
> setup_new_exec, the failure of unshare_sighand is the only
> code path where exec_update_mutex is held but not explicitly
> unlocked.
> 
> Update that code path to explicitly unlock exec_update_mutex.
> 
> Remove the unlocking of exec_update_mutex from free_bprm.
> 
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Yeah, assuming that I didn't miss any subtleties just now.
By "explicit" I assume you mean not conditionally unlocked, i.e. we
don't need to check any condition in free_binprm().

Acked-by: Christian Brauner <christian.brauner@...ntu.com>