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From:   OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     syzbot <syzbot+6f1624f937d9d6911e2d@syzkaller.appspotmail.com>,
        Marco Elver <elver@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: KCSAN: data-race in __fat_write_inode / fat12_ent_get
References: <0000000000000cfff005a26226ce@google.com>
        <874ku0sncc.fsf@mail.parknet.co.jp>
        <CACT4Y+YaM9Qj9V9G7G+aQrmfxfdtyBX4WXXsBamUjyMMpEeEdg@mail.gmail.com>
Date:   Sat, 04 Apr 2020 15:14:02 +0900
In-Reply-To: <CACT4Y+YaM9Qj9V9G7G+aQrmfxfdtyBX4WXXsBamUjyMMpEeEdg@mail.gmail.com>
        (Dmitry Vyukov's message of "Fri, 3 Apr 2020 18:36:26 +0200")
Message-ID: <877dyveq1h.fsf@mail.parknet.co.jp>
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Dmitry Vyukov <dvyukov@google.com> writes:

> On Fri, Apr 3, 2020 at 3:36 PM OGAWA Hirofumi
> <hirofumi@mail.parknet.co.jp> wrote:
>>
>> Hm, looks like the race between a directory entry vs a FAT entry.  This
>> bug was happened with the corrupted image? Or the image passes the check
>> of dosfsck?
>>
>> If the corrupted image, it may be hard to prevent the all races. Well,
>> anyway, the corrupted image of the report will help to detect this
>> corruption.
>
> From the log, it's this program.
> My bet on a corrupted image. syzkaller does not have format
> descriptions for fat, so it's just random bytes.

You meant I can regenerate a disk image from that log (if so, how)?

If not, for next time, it would be helpful if syzkaller provides the log
to regenerate the corrupted image (or saving a corrupted image) to
reproduce this, then I can try to detect the corruption pattern early.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>