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    Subject[PATCH 4.4 323/342] x86/irq: Fix a race in x86_vector_free_irqs()
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jiang Liu <jiang.liu@linux.intel.com>

    commit 111abeba67e0dbdc26537429de9155e4f1d807d8 upstream.

    There's a race condition between

    x86_vector_free_irqs()
    {
    free_apic_chip_data(irq_data->chip_data);
    xxxxx //irq_data->chip_data has been freed, but the pointer
    //hasn't been reset yet
    irq_domain_reset_irq_data(irq_data);
    }

    and

    smp_irq_move_cleanup_interrupt()
    {
    raw_spin_lock(&vector_lock);
    data = apic_chip_data(irq_desc_get_irq_data(desc));
    access data->xxxx // may access freed memory
    raw_spin_unlock(&desc->lock);
    }

    which may cause smp_irq_move_cleanup_interrupt() to access freed memory.

    Call irq_domain_reset_irq_data(), which clears the pointer with vector lock
    held.

    [ tglx: Free memory outside of lock held region. ]

    Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
    Tested-by: Borislav Petkov <bp@alien8.de>
    Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
    Cc: Jeremiah Mahler <jmmahler@gmail.com>
    Cc: andy.shevchenko@gmail.com
    Cc: Guenter Roeck <linux@roeck-us.net>
    Link: http://lkml.kernel.org/r/1450880014-11741-3-git-send-email-jiang.liu@linux.intel.com
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/kernel/apic/vector.c | 16 ++++++++--------
    1 file changed, 8 insertions(+), 8 deletions(-)

    --- a/arch/x86/kernel/apic/vector.c
    +++ b/arch/x86/kernel/apic/vector.c
    @@ -224,10 +224,8 @@ static int assign_irq_vector_policy(int
    static void clear_irq_vector(int irq, struct apic_chip_data *data)
    {
    struct irq_desc *desc;
    - unsigned long flags;
    int cpu, vector;

    - raw_spin_lock_irqsave(&vector_lock, flags);
    BUG_ON(!data->cfg.vector);

    vector = data->cfg.vector;
    @@ -237,10 +235,8 @@ static void clear_irq_vector(int irq, st
    data->cfg.vector = 0;
    cpumask_clear(data->domain);

    - if (likely(!data->move_in_progress)) {
    - raw_spin_unlock_irqrestore(&vector_lock, flags);
    + if (likely(!data->move_in_progress))
    return;
    - }

    desc = irq_to_desc(irq);
    for_each_cpu_and(cpu, data->old_domain, cpu_online_mask) {
    @@ -253,7 +249,6 @@ static void clear_irq_vector(int irq, st
    }
    }
    data->move_in_progress = 0;
    - raw_spin_unlock_irqrestore(&vector_lock, flags);
    }

    void init_irq_alloc_info(struct irq_alloc_info *info,
    @@ -274,19 +269,24 @@ void copy_irq_alloc_info(struct irq_allo
    static void x86_vector_free_irqs(struct irq_domain *domain,
    unsigned int virq, unsigned int nr_irqs)
    {
    + struct apic_chip_data *apic_data;
    struct irq_data *irq_data;
    + unsigned long flags;
    int i;

    for (i = 0; i < nr_irqs; i++) {
    irq_data = irq_domain_get_irq_data(x86_vector_domain, virq + i);
    if (irq_data && irq_data->chip_data) {
    + raw_spin_lock_irqsave(&vector_lock, flags);
    clear_irq_vector(virq + i, irq_data->chip_data);
    - free_apic_chip_data(irq_data->chip_data);
    + apic_data = irq_data->chip_data;
    + irq_domain_reset_irq_data(irq_data);
    + raw_spin_unlock_irqrestore(&vector_lock, flags);
    + free_apic_chip_data(apic_data);
    #ifdef CONFIG_X86_IO_APIC
    if (virq + i < nr_legacy_irqs())
    legacy_irq_data[virq + i] = NULL;
    #endif
    - irq_domain_reset_irq_data(irq_data);
    }
    }
    }
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