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From: Leon Romanovsky <leon@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Colin Ian King <colin.king@canonical.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH rdma-next 1/4] gcov: Open-code kmemdup() to work correctly with kernel and user space pointers
Date: Wed, 2 Sep 2020 20:46:00 +0300	[thread overview]
Message-ID: <20200902174600.GK59010@unreal> (raw)
In-Reply-To: <CAHk-=wiOJ4H=YFO8+EumOcrciQgeKXY1Z92jdqY8OQdprPXkbg@mail.gmail.com>

On Wed, Sep 02, 2020 at 10:38:20AM -0700, Linus Torvalds wrote:
> On Wed, Sep 2, 2020 at 1:55 AM Leon Romanovsky <leon@kernel.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?

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.

This is why I wrote "both user and kernel pointer".

Thanks

>
>              Linus

  reply	other threads:[~2020-09-02 17:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-02  8:55 [PATCH -rc 0/4] Protect from GCC garbage input in GCOV Leon Romanovsky
2020-09-02  8:55 ` [PATCH rdma-next 1/4] gcov: Open-code kmemdup() to work correctly with kernel and user space pointers Leon Romanovsky
2020-09-02 17:38   ` Linus Torvalds
2020-09-02 17:46     ` Leon Romanovsky [this message]
2020-09-02 18:27       ` Linus Torvalds
2020-09-02 18:44         ` Leon Romanovsky
2020-09-02 19:04           ` Linus Torvalds
2020-09-02  8:55 ` [PATCH rdma-next 2/4] gcov: Use proper duplication routine for const pointer Leon Romanovsky
2020-09-03  8:56   ` Rasmus Villemoes
2020-09-03 10:38     ` Leon Romanovsky
2020-09-02  8:55 ` [PATCH rdma-next 3/4] gcov: Protect from uninitialized number of functions provided by GCC 10.2 Leon Romanovsky
2020-09-02 17:41   ` Linus Torvalds
2020-09-02  8:55 ` [PATCH rdma-next 4/4] gcov: Don't print out-of-memory print for all failed files Leon Romanovsky
2020-09-02 17:42 ` [PATCH -rc 0/4] Protect from GCC garbage input in GCOV Linus Torvalds
2020-09-02 17:52   ` Leon Romanovsky
2020-09-02 18:24     ` Linus Torvalds
2020-09-02 18:28       ` Leon Romanovsky

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