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Groups > linux.kernel > #1620143

Re: [patch 2/3] x86/vdso: Plug race between mapping and ELF header setup

From Andy Lutomirski <luto@amacapital.net>
Newsgroups linux.kernel
Subject Re: [patch 2/3] x86/vdso: Plug race between mapping and ELF header setup
Date 2017-04-10 18:00 +0200
Message-ID <tuJTv-2D4-89@gated-at.bofh.it> (permalink)
References <tuJgJ-2nZ-1@gated-at.bofh.it> <tuJgK-2nZ-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Apr 10, 2017 at 8:14 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> The vsyscall32 sysctl can racy against a concurrent fork when it switches
> from disabled to enabled:
>
>     arch_setup_additional_pages()
>         if (vdso32_enabled)
>            --> No mapping
>                                         sysctl.vsysscall32()
>                                           --> vdso32_enabled = true
>     create_elf_tables()
>       ARCH_DLINFO_IA32
>         if (vdso32_enabled) {
>            --> Add VDSO entry with NULL pointer
>
> Make ARCH_DLINFO_IA32 check whether the VDSO mapping has been set up for
> the newly forked process or not.

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

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Thread

[patch 0/3] x86/vdso: Fix enable inconsistencies and cleanup Thomas Gleixner <tglx@linutronix.de> - 2017-04-10 17:20 +0200
  [patch 2/3] x86/vdso: Plug race between mapping and ELF header setup Thomas Gleixner <tglx@linutronix.de> - 2017-04-10 17:20 +0200
    Re: [patch 2/3] x86/vdso: Plug race between mapping and ELF header setup Andy Lutomirski <luto@amacapital.net> - 2017-04-10 18:00 +0200
    [tip:x86/urgent] x86/vdso: Plug race between mapping and ELF header  setup tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-10 20:00 +0200
  [patch 3/3] x86/vdso: Sanitize vdso*_enabled handling Thomas Gleixner <tglx@linutronix.de> - 2017-04-10 17:20 +0200
    Re: [patch 3/3] x86/vdso: Sanitize vdso*_enabled handling Andy Lutomirski <luto@amacapital.net> - 2017-04-10 18:00 +0200
      Re: [patch 3/3] x86/vdso: Sanitize vdso*_enabled handling Thomas Gleixner <tglx@linutronix.de> - 2017-04-10 18:30 +0200
  [patch 1/3] x86/vdso: Ensure vdso32_enabled gets set to valid values  only Thomas Gleixner <tglx@linutronix.de> - 2017-04-10 17:20 +0200
    [tip:x86/urgent] x86/vdso: Ensure vdso32_enabled gets set to valid  values only tip-bot for Mathias Krause <tipbot@zytor.com> - 2017-04-10 18:40 +0200

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