linux-kernel - Re: [PATCH] time: Zerofy padding in __kernel

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Message-ID: <CAK8P3a2ny7SBwQbNcn5nxYrZ9pX1Vh5P2PFXVpOFaquTcFguCA@mail.gmail.com>
Date:   Thu, 21 Nov 2019 10:06:57 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Dmitry Safonov <dima@...sta.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        John Stultz <john.stultz@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        y2038 Mailman List <y2038@...ts.linaro.org>,
        "# 3.4.x" <stable@...r.kernel.org>
Subject: Re: [PATCH] time: Zerofy padding in __kernel_timespec on 32-bit

On Thu, Nov 21, 2019 at 1:03 AM Dmitry Safonov <dima@...sta.com> wrote:
>
> On compat interfaces, the high order bits of nanoseconds should
> be zeroed out. This is because the application code or the libc
> do not guarantee zeroing of these. If used without zeroing,
> kernel might be at risk of using timespec values incorrectly.
>
> Originally it was handled correctly, but lost during is_compat_syscall()
> cleanup. Revert the condition back to check CONFIG_64BIT.
>
> Reported-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
> Fixes: 98f76206b335 ("compat: Cleanup in_compat_syscall() callers")

Reviewed-by: Arnd Bergmann <arnd@...db.de>