From: Hristo Venev <[email protected]>
To: Dmitry Vyukov <[email protected]>, Jens Axboe <[email protected]>
Cc: Necip Fazil Yildiran <[email protected]>, [email protected]
Subject: Re: [PATCH] io_uring: fix sq array offset calculation
Date: Sat, 11 Jul 2020 18:52:19 +0300 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <CACT4Y+YGwr+1k=rsJhMsnyQL4C+S2s9t7Cz5Axwc9fO5Ap4HbQ@mail.gmail.com>
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On Sat, 2020-07-11 at 17:31 +0200, Dmitry Vyukov wrote:
> Looking at the code more, I am not sure how it may not corrupt
> memory.
> There definitely should be some combinations where accessing
> sq_entries*sizeof(u32) more memory won't be OK.
> May be worth adding a test that allocates all possible sizes for
> sq/cq
> and fills both rings.
The layout (after the fix) is roughly as follows:
1. struct io_rings - ~192 bytes, maybe 256
2. cqes - (32 << n) bytes
3. sq_array - (4 << n) bytes
The bug was that the sq_array was offset by (4 << n) bytes. I think
issues can only occur when
PAGE_ALIGN(192 + (32 << n) + (4 << n) + (4 << n))
!=
PAGE_ALIGN(192 + (32 << n) + (4 << n))
It looks like this never happens. We got lucky.
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next prev parent reply other threads:[~2020-07-11 15:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-11 9:31 [PATCH] io_uring: fix sq array offset calculation Dmitry Vyukov
2020-07-11 9:37 ` Hristo Venev
2020-07-11 15:15 ` Jens Axboe
2020-07-11 15:31 ` Dmitry Vyukov
2020-07-11 15:36 ` Jens Axboe
2020-07-11 15:47 ` Jens Axboe
2020-07-11 15:52 ` Hristo Venev [this message]
2020-07-11 15:55 ` Jens Axboe
2020-07-11 15:56 ` Hristo Venev
2020-07-11 16:16 ` Dmitry Vyukov
2020-07-17 13:48 ` Dmitry Vyukov
2020-07-17 14:05 ` Jens Axboe
2020-07-17 14:08 ` Jens Axboe
2020-07-17 14:08 ` Dmitry Vyukov
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