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From: Dmitry Vyukov <dvyukov@google.com>
To: Tigran Aivazian <aivazian.tigran@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	syzbot <syzbot+71c6b5d68e91149fc8a4@syzkaller.appspotmail.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH] bfs: add sanity check at bfs_fill_super().
Date: Thu, 14 Jun 2018 15:12:53 +0200	[thread overview]
Message-ID: <CACT4Y+afDT9jgsmxKiDXp--6Pw3UO2y92EYwM2zyCw0E3VoEUg@mail.gmail.com> (raw)
In-Reply-To: <CAK+_RLmxrdtxSxL-iVUfAgRAuSdC7hVV6QUZYxU5PDQUL-4nDg@mail.gmail.com>

On Thu, Jun 14, 2018 at 3:05 PM, Tigran Aivazian
<aivazian.tigran@gmail.com> wrote:
> On 14 June 2018 at 13:38, Dmitry Vyukov <dvyukov@google.com> wrote:
>> Consider, currently we can have a bfs image that works fine on one
>> kernel, but fails to mount on another just because it happens so that
>> one could allocate 4MB with kmalloc, but another can't (different
>> allocator/different settings/different kernel revision).
>
> Yes, but this would only happen _without_ the validation proposed by
> Tetsuo Handa. If we check s_start then the invalid enormous allocation
> request will not be made and what you describe won't not happen.

Agree. If we do a sanity check first, then __GFP_NOWARN is actually
useful: it will detect the cases where a filesystem can be mounted on
one machine but not on another (and will also double check that our
sanity is really sane).

  reply	other threads:[~2018-06-14 13:13 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-09 10:35 [PATCH] bfs: add sanity check at bfs_fill_super() Tetsuo Handa
2018-05-09 23:06 ` Andrew Morton
     [not found]   ` <201805092346.w49NkINl045657@www262.sakura.ne.jp>
2018-05-09 23:53     ` Andrew Morton
2018-06-13 13:33       ` Tetsuo Handa
2018-06-13 13:49         ` Tigran Aivazian
2018-06-13 16:00           ` Dmitry Vyukov
2018-06-14 12:23             ` Tigran Aivazian
2018-06-14 12:38               ` Dmitry Vyukov
2018-06-14 13:05                 ` Tigran Aivazian
2018-06-14 13:12                   ` Dmitry Vyukov [this message]
2018-06-14 13:28                   ` Tetsuo Handa
2018-06-14 15:13                     ` Tigran Aivazian
2018-06-14 16:15                       ` Tigran Aivazian
2018-06-14 19:00                         ` Tigran Aivazian
2018-06-14 22:18                           ` Tetsuo Handa
2018-06-15 10:45                             ` Tigran Aivazian
2018-06-13 22:09           ` Tetsuo Handa
2018-06-14  7:38             ` Tigran Aivazian
2018-06-14 10:45               ` Tetsuo Handa
2018-06-14 12:11                 ` Tigran Aivazian
2018-05-10  0:53 ` Matthew Wilcox

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