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-=whG7MPx0_6S8ATd4yRPtwKTThDNtbKQDQARHbaPp2H1Wg@mail.gmail.com>
Date:   Wed, 2 Sep 2020 11:27:14 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Peter Oberparleiter <oberpar@...ux.ibm.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 10:46 AM Leon Romanovsky <leon@...nel.org> wrote:
>
> Definitely my explanation is wrong, but it was my interpretation of
> "BUG: KASAN: global-out-of-bounds in kmemdup+0x43/0x70" line. I saw
> that the failure was in memcpy() inside of kmemdup(), so I changed
> from memcpy to be copy_from_user() and it solved the KASAN warning.

But the actual patch attached to that explanation *doesn't* use
copy_from_user().

So your "changed from memcpy to be copy_from_user() solved the KASAN
warning" explanation makes even less sense. Because that's not at all
what the patch does.

             Linus