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Message-ID: <20170510064957.GB4115@infradead.org>
Date: Tue, 9 May 2017 23:49:57 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Al Viro <viro@...IV.linux.org.uk>
Cc: Christoph Hellwig <hch@...radead.org>,
Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...nel.org>,
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Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: Re: [PATCH v9 1/4] syscalls: Verify address
limit before returning to user-mode
On Wed, May 10, 2017 at 03:45:24AM +0100, Al Viro wrote:
> FWIW, some parts of that queue are obviously sane; it's the conversions of
> kernel_write() and friends to ->read_iter/->write_iter() that are non-starters.
And that part is the main point!
> That stuff is used in too many situations; we can't guarantee that all of
> them will be for files that have those.
That's why this series handles ITER_KVEC for this case, which is all
that's really needed for kernel_read/write. If you insiste the bvec
and pipe cases are handled as well that couod be added fairly easily.
> As for default_file_splice_read(), I seriously suspect that with your change
> we could as well just make it return -EINVAL and be done with that; places
> that have ->read_iter() tend to have explicit ->splice_read() and it looks
> like the ones that do not should simply use generic_file_read_iter().
> I hadn't checked that, but there's not a lot of those:
Making ->splice_read to default to the ->read_iter based implementation
and returning -EINVAL if neither that nor an explicit ->splice_read
is provided is useful, but wasn't the aim of this series. Similar
on the write side.
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