linux-kernel - Re: [PATCH v2 0/2] iter revert problems

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Message-ID: <221d06f1-7e6b-c48f-57e8-45111c979217@kernel.dk>
Date:   Mon, 16 Aug 2021 09:35:12 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>, io-uring@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Cc:     Palash Oswal <oswalpalash@...il.com>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        linux-kernel@...r.kernel.org,
        syzbot+9671693590ef5aad8953@...kaller.appspotmail.com
Subject: Re: [PATCH v2 0/2] iter revert problems

On 8/12/21 2:40 PM, Pavel Begunkov wrote:
> For the bug description see 2/2. 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 it has been justly fully reverted

Al, what do you think of this approach? It'll fix the issue, but might be
cleaner to have iov->truncated actually track the truncated size. That'd
make it a more complete solution, at the expense of bloat iov_iter which
this version will not.

-- 
Jens Axboe