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Subject: Re: [PATCH] kernel: introduce prctl(PR_LOG_UACCESS)
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Peter Collingbourne <pcc@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
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        Andy Lutomirski <luto@kernel.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
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From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <4d70ee3c-ab2a-a0e3-0214-8cc65caf2acd@redhat.com>
Date:   Thu, 23 Sep 2021 10:08:28 +0200
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On 22.09.21 21:22, Steven Rostedt wrote:
> On Wed, 22 Sep 2021 19:46:47 +0200
> David Hildenbrand <david@redhat.com> wrote:
> 
>>> All signals except SIGKILL and SIGSTOP are masked for the interval
>>> between the prctl() and the next syscall in order to prevent handlers
>>> for intervening asynchronous signals from issuing syscalls that may
>>> cause uaccesses from the wrong syscall to be logged.
>>
>> Stupid question: can this be exploited from user space to effectively
>> disable SIGKILL for a long time ... and do we care?
> 
> I first misread it too, but then caught my mistake reading it a second
> time. It says "except SIGKILL". So no, it does not disable SIGKILL.

Thanks for pointing out the obvious Steve :)

-- 
Thanks,

David / dhildenb