linux-kernel - Re: [PATCH] x86/vdso: ensure vdso32_enabled gets set to valid values only

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Date:   Thu, 6 Apr 2017 08:59:38 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Mathias Krause <minipli@...glemail.com>
Cc:     X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Roland McGrath <roland@...hat.com>
Subject: Re: [PATCH] x86/vdso: ensure vdso32_enabled gets set to valid values only

On Wed, Apr 5, 2017 at 1:36 PM, Mathias Krause <minipli@...glemail.com> wrote:
> If either via kernel command line 'vdso32=' or via 'sysctl abi.vsyscall32'
> vdso32_enabled gets set to a value below 0 or above 1, load_vdso32() won't
> map the vDSO but ARCH_DLINFO_IA32 would still pass an AT_SYSINFO_EHDR
> auxiliary vector, however with a NULL pointer. That'll make any program
> trying to make use of it fail with a segmentation fault. At least musl
> makes use of it if the kernel provides it.
>
> Ensure vdso32_enabled gets set to valid values only to fix this corner
> case.

Acked-by: Andy Lutomirski <luto@...nel.org>