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Date: Tue, 23 Jan 2024 16:09:12 -0800
From: Kees Cook <keescook@chromium.org>
To: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Oleg Nesterov <oleg@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Alexey Dobriyan <adobriyan@gmail.com>,
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	Jan Kara <jack@suse.cz>, David Hildenbrand <david@redhat.com>,
	Dave Chinner <dchinner@redhat.com>, Shuah Khan <shuah@kernel.org>,
	Zheng Yejian <zhengyejian1@huawei.com>,
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Subject: Re: [PATCH v14] exec: Fix dead-lock in de_thread with ptrace_attach
Message-ID: <202401231555.59B7EDBB2@keescook>
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On Tue, Jan 23, 2024 at 07:30:52PM +0100, Bernd Edlinger wrote:
> - Currently a non-privileged program can potentially send such a privileged
> tracer into a deadlock.
> - With the alternative patch below that non-privileged can no longer send the
> tracer into a deadlock, but it can still quickly escape out of the tracer's
> control.
> - But with my latest patch a sufficiently privileged tracer can neither be
> sent into a deadlock nor can the attached process escape.  Mission completed.

Thanks for the details. And it would be pretty unfriendly to fail the execve()
too (or, rather, it makes the execve failure unpredictable). I'll keep
reading your patch...

-- 
Kees Cook