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Date:   Wed, 25 Mar 2020 16:41:33 +0100
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Andrei Vagin <avagin@gmail.com>,
        Ingo Molnar <mingo@kernel.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Yuyang Du <duyuyang@gmail.com>,
        David Hildenbrand <david@redhat.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        David Howells <dhowells@redhat.com>,
        James Morris <jamorris@linux.microsoft.com>,
        Shakeel Butt <shakeelb@google.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Christian Kellner <christian@kellner.me>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        "Dmitry V. Levin" <ldv@altlinux.org>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-api@vger.kernel.org" <linux-api@vger.kernel.org>
Subject: Re: [PATCH v6 10/16] kernel/kcmp.c: Use new infrastructure to fix
 deadlocks in execve
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On Fri, Mar 20, 2020 at 09:27:05PM +0100, Bernd Edlinger wrote:
> This changes kcmp_epoll_target to use the new exec_update_mutex
> instead of cred_guard_mutex.
> 
> This should be safe, as the credentials are only used for reading,
> and furthermore ->mm and ->sighand are updated on execve,
> but only under the new exec_update_mutex.
> 
> Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>

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