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From:   Xiaomeng Tong <xiam0nd.tong@gmail.com>
To:     sj@kernel.org
Cc:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, stable@vger.kernel.org, xiam0nd.tong@gmail.com
Subject: Re: [PATCH] damon: vaddr-test: fix a missing check on list iterator
Date:   Mon, 28 Mar 2022 19:36:04 +0800
Message-Id: <20220328113604.31373-1-xiam0nd.tong@gmail.com>
In-Reply-To: <20220328075104.31125-1-sj@kernel.org>
References: <20220328075104.31125-1-sj@kernel.org>
Precedence: bulk

On  Mon, 28 Mar 2022 07:51:04 +0000, SJ wrote:
> On Sun, 27 Mar 2022 16:03:45 +0800 Xiaomeng Tong <xiam0nd.tong@gmail.com> wrote:
> 
> > The bug is here:
> > 	KUNIT_EXPECT_EQ(test, r->ar.start, start + i * expected_width);
> > 	KUNIT_EXPECT_EQ(test, r->ar.end, end);
> > 
> > For the damon_for_each_region(), just like list_for_each_entry(),
> > the list iterator 'drm_crtc' will point to a bogus position
> > containing HEAD if the list is empty or no element is found.
> > This case must be checked before any use of the iterator,
> > otherwise it will lead to a invalid memory access.
> 
> We ensure 'damon_va_evenly_split_region()' successes before executing the loop,
> so the issue cannot occur.  That said, I think this patch makes code better to
> read.  Could you please resend this patch after fixing the commit message?

Yes, you should be right. I have resend this patch with the commit message changed.
Please check it, thank you.

--
Xiaomeng Tong