From: PanBian <bianpan2016@163.com>
To: Chao Yu <yuchao0@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>,
linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH] f2fs: read page index before freeing
Date: Mon, 26 Nov 2018 18:28:41 +0800 [thread overview]
Message-ID: <20181126102841.GA94853@bp> (raw)
In-Reply-To: <3ebe6814-586e-77e8-52fa-47fb61d760f5@huawei.com>
On Mon, Nov 26, 2018 at 05:13:53PM +0800, Chao Yu wrote:
> Hi Pan,
>
> On 2018/11/22 18:58, Pan Bian wrote:
> > The function truncate_node frees the page with f2fs_put_page. However,
> > the page index is read after that. So, the patch reads the index before
> > freeing the page.
>
> I notice that you found another use-after-free bug in ext4, out of
> curiosity, I'd like to ask how do you find those bugs? by tool or code review?
I found such bugs by the aid of a tool I wrote recently. I designed a method
to automatically find paired alloc/free functions. With such functions, I
wrote two checkers, one to check mismatched alloc/free bugs, the other to
check use-after-free and double-free bugs.
Best regards,
Pan Bian
WARNING: multiple messages have this Message-ID (diff)
From: PanBian <bianpan2016@163.com>
To: Chao Yu <yuchao0@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>,
linux-f2fs-devel@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] f2fs: read page index before freeing
Date: Mon, 26 Nov 2018 18:28:41 +0800 [thread overview]
Message-ID: <20181126102841.GA94853@bp> (raw)
In-Reply-To: <3ebe6814-586e-77e8-52fa-47fb61d760f5@huawei.com>
On Mon, Nov 26, 2018 at 05:13:53PM +0800, Chao Yu wrote:
> Hi Pan,
>
> On 2018/11/22 18:58, Pan Bian wrote:
> > The function truncate_node frees the page with f2fs_put_page. However,
> > the page index is read after that. So, the patch reads the index before
> > freeing the page.
>
> I notice that you found another use-after-free bug in ext4, out of
> curiosity, I'd like to ask how do you find those bugs? by tool or code review?
I found such bugs by the aid of a tool I wrote recently. I designed a method
to automatically find paired alloc/free functions. With such functions, I
wrote two checkers, one to check mismatched alloc/free bugs, the other to
check use-after-free and double-free bugs.
Best regards,
Pan Bian
next prev parent reply other threads:[~2018-11-26 10:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 10:58 [PATCH] f2fs: read page index before freeing Pan Bian
2018-11-22 11:21 ` Chao Yu
2018-11-22 11:21 ` Chao Yu
2018-11-22 12:02 ` Jaegeuk Kim
2018-11-26 9:13 ` Chao Yu
2018-11-26 9:13 ` Chao Yu
2018-11-26 10:28 ` PanBian [this message]
2018-11-26 10:28 ` PanBian
2018-11-26 11:07 ` Chao Yu
2018-11-26 11:07 ` Chao Yu
2018-11-27 0:22 ` PanBian
2018-11-27 3:12 ` Chao Yu
2018-11-27 3:12 ` Chao Yu
2018-11-27 3:22 ` PanBian
2018-11-27 3:22 ` PanBian
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