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Date:   Sat, 20 Aug 2022 12:03:48 -0400 (EDT)
From:   Mikulas Patocka <mpatocka@redhat.com>
To:     Pavel Machek <pavel@denx.de>
cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Song Liu <song@kernel.org>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 5.15 089/779] md-raid10: fix KASAN warning
In-Reply-To: <20220819104534.GA11901@duo.ucw.cz>
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References: <20220815180337.130757997@linuxfoundation.org> <20220815180341.087873206@linuxfoundation.org> <20220819104534.GA11901@duo.ucw.cz>
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On Fri, 19 Aug 2022, Pavel Machek wrote:

> Hi!
> 
> > From: Mikulas Patocka <mpatocka@redhat.com>
> > 
> > commit d17f744e883b2f8d13cca252d71cfe8ace346f7d upstream.
> > 
> > There's a KASAN warning in raid10_remove_disk when running the lvm
> > test lvconvert-raid-reshape.sh. We fix this warning by verifying that the
> > value "number" is valid.
> > 
> > BUG: KASAN: slab-out-of-bounds in raid10_remove_disk+0x61/0x2a0 [raid10]
> > Read of size 8 at addr ffff889108f3d300 by task mdX_raid10/124682
> 
> Is this place for array_index_nospec?
> 
> Best regards,
> 								Pavel

Hi

I think it is not needed - userspace code can't trigger this code path at 
will.

Mikulas