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From: Rich Felker <>
Subject: Re: [musl] [PATCH] accept4: don't fall back to accept if we got unknown flags
Date: Mon, 27 Feb 2023 17:38:23 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Mon, Feb 27, 2023 at 10:46:54PM +0300, Alexey Izbyshev wrote:
> accept4 emulation via accept ignores unknown flags, so it can spuriously
> succeed instead of failing (or succeed without doing the action implied
> by an unknown flag if it's added in a future kernel). Worse, unknown
> flags trigger the fallback code even on modern kernels if the real
> accept4 syscall returns EINVAL, because this is indistinguishable from
> socketcall returning EINVAL due to lack of accept4 support. Fix this by
> always propagating the syscall attempt failure if unknown flags are
> present.
> The behavior is still not ideal on old kernels lacking accept4 on arches
> with socketcall, where failing with ENOSYS instead of EINVAL returned by
> socketcall would be preferable, but at least modern kernels are now
> fine.

Can you clarify what you mean about ENOSYS vs EINVAL here? I'm not


  reply	other threads:[~2023-02-27 22:38 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-27 19:46 Alexey Izbyshev
2023-02-27 22:38 ` Rich Felker [this message]
2023-02-27 23:42   ` Alexey Izbyshev
2023-02-27 23:51     ` Alexey Izbyshev
2023-02-27 23:53       ` Rich Felker
2023-02-28 17:21     ` Rich Felker
2023-02-28 17:25       ` Rich Felker
2023-02-28 20:15         ` Alexey Izbyshev
2023-02-28 20:51           ` Rich Felker

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