From: Al Viro <viro@zeniv.linux.org.uk>
To: Edward Adam Davis <eadavis@qq.com>
Cc: syzbot+d3c29ed63db6ddf8406e@syzkaller.appspotmail.com,
hirofumi@mail.parknet.co.jp, linkinjeon@kernel.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
sj1557.seo@samsung.com, syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH] fat: Prevent the race of read/write the FAT16 and FAT32 entry
Date: Mon, 28 Jul 2025 17:04:45 +0100 [thread overview]
Message-ID: <20250728160445.GC222315@ZenIV> (raw)
In-Reply-To: <tencent_E34B081B4A25E3BA9DBBB733019E4E1BD408@qq.com>
On Mon, Jul 28, 2025 at 07:37:02PM +0800, Edward Adam Davis wrote:
> The writer and reader access FAT32 entry without any lock, so the data
> obtained by the reader is incomplete.
Could you be more specific? "Incomplete" in which sense?
> Add spin lock to solve the race condition that occurs when accessing
> FAT32 entry.
Which race condition would that be?
> FAT16 entry has the same issue and is handled together.
FWIW, I strongly suspect that
* "issue" with FAT32 is a red herring coming from mindless parroting
of dumb tool output
* issue with FAT16 just might be real, if architecture-specific.
If 16bit stores are done as 32bit read-modify-write, we might need some
serialization. Assuming we still have such architectures, that is -
alpha used to be one, but support for pre-BWX models got dropped.
Sufficiently ancient ARM?
next prev parent reply other threads:[~2025-07-28 16:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-28 8:17 [syzbot] [exfat?] KCSAN: data-race in fat32_ent_get / fat32_ent_put syzbot
2025-07-28 11:37 ` [PATCH] fat: Prevent the race of read/write the FAT16 and FAT32 entry Edward Adam Davis
2025-07-28 15:10 ` OGAWA Hirofumi
2025-07-29 3:57 ` Edward Adam Davis
2025-07-28 16:04 ` Al Viro [this message]
2025-07-28 16:35 ` Al Viro
2025-07-29 4:17 ` Edward Adam Davis
2025-07-29 4:53 ` Al Viro
2025-07-29 5:04 ` Al Viro
2025-07-29 5:32 ` Edward Adam Davis
2025-07-29 6:17 ` [PATCH V2] fat: Prevent the race of read/write the " Edward Adam Davis
2025-07-29 9:03 ` OGAWA Hirofumi
2025-07-29 9:35 ` Al Viro
2025-07-29 10:06 ` Al Viro
2025-08-18 13:58 ` Edward Adam Davis
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250728160445.GC222315@ZenIV \
--to=viro@zeniv.linux.org.uk \
--cc=eadavis@qq.com \
--cc=hirofumi@mail.parknet.co.jp \
--cc=linkinjeon@kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=sj1557.seo@samsung.com \
--cc=syzbot+d3c29ed63db6ddf8406e@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox