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References: <20200427200626.1622060-2-hch@lst.de> <20200428120207.15728-1-jk@ozlabs.org>
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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Tue, 28 Apr 2020 18:00:27 +0200
Message-ID: <CAK8P3a3ytp2eLa8sfC0se5fR-DFxMjqEh8_Y2N4PeH-yo1nhxw@mail.gmail.com>
Subject: Re: [RFC PATCH] powerpc/spufs: fix copy_to_user while atomic
To:     Jeremy Kerr <jk@ozlabs.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@lst.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Tue, Apr 28, 2020 at 2:05 PM Jeremy Kerr <jk@ozlabs.org> wrote:
>
> Currently, we may perform a copy_to_user (through
> simple_read_from_buffer()) while holding a context's register_lock,
> while accessing the context save area.
>
> This change uses a temporary buffers for the context save area data,
> which we then pass to simple_read_from_buffer.
>
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> ---

Thanks for fixing this!

I wonder how far it should be backported, given that this has been broken for
14 years now.

Fixes: bf1ab978be23 ("[POWERPC] coredump: Add SPU elf notes to coredump.")
Reviewed-by: Arnd Bergmann <arnd@arndb.de>