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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
	io-uring@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Cc: Palash Oswal <oswalpalash@gmail.com>,
	Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
	linux-kernel@vger.kernel.org,
	syzbot+9671693590ef5aad8953@syzkaller.appspotmail.com,
	asml.silence@gmail.com
Subject: [PATCH v3 0/2] iter revert problems
Date: Mon, 23 Aug 2021 11:18:43 +0100	[thread overview]
Message-ID: <cover.1629713020.git.asml.silence@gmail.com> (raw)

iov_iter_revert() doesn't go well with iov_iter_truncate() in all
cases, see 2/2 for the bug description. As mentioned there the current
problems is because of generic_write_checks(), but there was also a
similar case fixed in 5.12, which should have been triggerable by normal
write(2)/read(2) and others.

It may be better to enforce reexpands as a long term solution, but for
now this patchset is quickier and easier to backport.

v2: don't fail if it was justly fully reverted
v3: use truncated size + reexapand based approach

Pavel Begunkov (2):
  iov_iter: track truncated size
  io_uring: reexpand under-reexpanded iters

 fs/io_uring.c       | 2 ++
 include/linux/uio.h | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

-- 
2.32.0


             reply	other threads:[~2021-08-23 10:19 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 10:18 Pavel Begunkov [this message]
2021-08-23 10:18 ` [PATCH v3 1/2] iov_iter: track truncated size Pavel Begunkov
2021-08-23 10:18 ` [PATCH v3 2/2] io_uring: reexpand under-reexpanded iters Pavel Begunkov
2021-08-23 16:14 ` [PATCH v3 0/2] iter revert problems Jens Axboe
2021-09-03 20:55 ` Jens Axboe
2021-09-03 21:55   ` Al Viro
2021-09-04  0:57     ` Jens Axboe

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