linux-kernel - Re: [PATCH rdma-next 1/4] gcov: Open-code kmemdup() to work correctly with kernel and user space pointers

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Message-ID: <CAHk-=wiOJ4H=YFO8+EumOcrciQgeKXY1Z92jdqY8OQdprPXkbg@mail.gmail.com>
Date:   Wed, 2 Sep 2020 10:38:20 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Leon Romanovsky <leonro@...dia.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Colin Ian King <colin.king@...onical.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH rdma-next 1/4] gcov: Open-code kmemdup() to work correctly
 with kernel and user space pointers

On Wed, Sep 2, 2020 at 1:55 AM Leon Romanovsky <leon@...nel.org> wrote:
>
> The kernel with KASAN and GCOV enabled generates the following splat
> due to the situation that gcov_info can be both user and kernel pointer.

I can't parse the above explanation..

> It is triggered by the memcpy() inside kmemdup(), so as a possible solution
> let's copy fields manually.

.. and I don't see why copying the fields manually makes a difference.

Can you explain more?

             Linus