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