From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: "Pali Rohár" <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fat: Relax checks for sector size and media type
Date: Mon, 03 Sep 2018 17:01:03 +0900 [thread overview]
Message-ID: <874lf7t3gg.fsf@mail.parknet.co.jp> (raw)
In-Reply-To: <20180903074005.7e3guj24ksq2l44c@pali> ("Pali =?iso-8859-1?Q?Roh=E1r=22's?= message of "Mon, 3 Sep 2018 09:40:05 +0200")
Pali Roh�r <pali.rohar@gmail.com> writes:
>> Just relaxing validation doesn't work. The block layer doesn't support
>> smaller than 512, and lager than PAGE_SIZE. (And in specification, fat
>> doesn't support lager than 4096.)
>
> Hi! I just sent this patch for discussion, with links to (now open
> source) Windows implementation. I guess that Windows driver
> implementation is more "authoritative" then Microsoft's own
> specification. It is known that Windows implementation does not match
> Microsoft specification.
>
> I know at least 3 FAT specifications (MS EFI FAT, MS/SD card FAT,
> ECMA-107) and you are right that Microsoft's one does not allow sector
> sizes larger then 4096.
>
> If there is limitation by block layer, then:
>
> 1) Why we do not check for PAGE_SIZE?
That source seems to check power_of_2(size) and 128 <= size <=
4096. Rather why do you want to support larger than 4096? Or I'm missing
something?
> 2) Is check in fat driver really needed (if block layer checks it)?
Yes, isolating block layer error and fat format error to be better error
report.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
next prev parent reply other threads:[~2018-09-03 12:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-02 13:19 [PATCH] fat: Relax checks for sector size and media type Pali Rohár
2018-09-03 7:17 ` OGAWA Hirofumi
2018-09-03 7:40 ` Pali Rohár
2018-09-03 8:01 ` OGAWA Hirofumi [this message]
2018-09-03 8:04 ` Pali Rohár
2018-09-03 8:19 ` OGAWA Hirofumi
2018-09-12 10:17 ` Pali Rohár
2018-09-12 10:36 ` OGAWA Hirofumi
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