From: Andy Lutomirski <luto@amacapital.net>
To: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>,
linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, io-uring@vger.kernel.org
Subject: Re: io_uring vs in_compat_syscall()
Date: Mon, 20 Jul 2020 09:58:37 -0700 [thread overview]
Message-ID: <BACE670C-6A65-4D86-BC5F-A7EA267C3140@amacapital.net> (raw)
In-Reply-To: <ceb21006-26d0-b216-84a9-5da0b89b5fbf@kernel.dk>
> On Jul 20, 2020, at 9:37 AM, Jens Axboe <axboe@kernel.dk> wrote:
>
> On 7/20/20 12:10 AM, Christoph Hellwig wrote:
>> Hi Jens,
>>
>> I just found a (so far theoretical) issue with the io_uring submission
>> offloading to workqueues or threads. We have lots of places using
>> in_compat_syscall() to check if a syscall needs compat treatmenet.
>> While the biggest users is iocttl(), we also have a fair amount of
>> places using in_compat_task() in read and write methods, and these
>> will not do the wrong thing when used with io_uring under certain
>> conditions. I'm not sure how to best fix this, except for making sure
>> in_compat_syscall() returns true one way or another for these cases.
>
> We can probably propagate this information in the io_kiocb via a flag,
> and have the io-wq worker set TS_COMPAT if that's the case.
>
Is TS_COMPAT actually a cross-arch concept for which this is safe? Having a real arch helper for “set the current syscall arch for the current kernel thread” seems more sensible to me.
next prev parent reply other threads:[~2020-07-20 16:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 6:10 io_uring vs in_compat_syscall() Christoph Hellwig
2020-07-20 16:36 ` Jens Axboe
2020-07-20 16:58 ` Andy Lutomirski [this message]
2020-07-20 17:02 ` Jens Axboe
2020-07-20 17:28 ` Andy Lutomirski
2020-07-21 7:07 ` Christoph Hellwig
2020-07-21 14:31 ` Andy Lutomirski
2020-07-21 14:34 ` Christoph Hellwig
2020-07-21 17:25 ` Andy Lutomirski
2020-07-22 6:30 ` Christoph Hellwig
2020-07-22 8:39 ` David Laight
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