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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Mon, 30 Dec 2019 13:26:49 +0100
Message-ID: <CAHmME9o07dQV_MmWmtBFCKp=sdsO-scC6-UbXNi=dpU6umCoPg@mail.gmail.com>
Subject: Re: [PATCH] mips: vdso: conditionalize 32-bit time functions on COMPAT_32BIT_TIME
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
        Paul Burton <paulburton@kernel.org>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Christian Brauner <christian.brauner@canonical.com>
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On Mon, Dec 30, 2019 at 12:58 PM Arnd Bergmann <arnd@arndb.de> wrote:
> Thanks for the bug report! I'm not completely sure why this fails in
> this particular
> way though. I assume you are using musl-1.1.20, not a musl-1.2.0 snapshot

Yes, that's the one, sorry.

> diff --git a/arch/mips/vdso/vdso.lds.S b/arch/mips/vdso/vdso.lds.S
> index da4627430aba..0bdc6a026be8 100644
> --- a/arch/mips/vdso/vdso.lds.S
> +++ b/arch/mips/vdso/vdso.lds.S
> @@ -93,9 +93,11 @@ VERSION
>         LINUX_2.6 {
>  #ifndef DISABLE_MIPS_VDSO
>         global:
> +#if (_MIPS_SIM == _MIPS_SIM_ABI64) || defined(CONFIG_COMPAT_32BIT_TIME)
>                 __vdso_clock_gettime;
>                 __vdso_gettimeofday;
>                 __vdso_clock_getres;
> +#endif
>  #if _MIPS_SIM != _MIPS_SIM_ABI64
>                 __vdso_clock_gettime64;
>  #endif
>
> That should ensure that no user space can call the old vdso
> functions on a kernel that intentionally breaks the actual
> syscalls.

I can confirm that patch fixes things. Thanks.

Jason