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    Subject[tip:irq/core] genirq: Prevent crash in irq_move_irq()
    Commit-ID:  77ed42f18edd486e9994ccd1f174076309a6343f
    Gitweb: http://git.kernel.org/tip/77ed42f18edd486e9994ccd1f174076309a6343f
    Author: Jiang Liu <jiang.liu@linux.intel.com>
    AuthorDate: Mon, 1 Jun 2015 16:05:11 +0800
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Fri, 12 Jun 2015 16:54:21 +0200

    genirq: Prevent crash in irq_move_irq()

    The functions irq_move_irq() and irq_move_masked_irq() expect that the
    caller passes the top-level irq_data to them when hierarchical
    irqdomains are enabled. But that's not true when called from
    apic_ack_edge(), which results in a null pointer dereference by
    idata->chip->irq_mask(idata).

    Instead of fixing callers to passing top-level irq_data, we rather
    change irq_move_irq()/irq_move_masked_irq() to accept any irq_data.

    Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
    Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Bjorn Helgaas <bhelgaas@google.com>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Randy Dunlap <rdunlap@infradead.org>
    Cc: Yinghai Lu <yinghai@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Link: http://lkml.kernel.org/r/1433145945-789-3-git-send-email-jiang.liu@linux.intel.com
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    kernel/irq/migration.c | 9 ++++++++-
    1 file changed, 8 insertions(+), 1 deletion(-)

    diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
    index ca3f4aa..dd203e2 100644
    --- a/kernel/irq/migration.c
    +++ b/kernel/irq/migration.c
    @@ -7,7 +7,7 @@
    void irq_move_masked_irq(struct irq_data *idata)
    {
    struct irq_desc *desc = irq_data_to_desc(idata);
    - struct irq_chip *chip = idata->chip;
    + struct irq_chip *chip = desc->irq_data.chip;

    if (likely(!irqd_is_setaffinity_pending(&desc->irq_data)))
    return;
    @@ -52,6 +52,13 @@ void irq_move_irq(struct irq_data *idata)
    {
    bool masked;

    + /*
    + * Get top level irq_data when CONFIG_IRQ_DOMAIN_HIERARCHY is enabled,
    + * and it should be optimized away when CONFIG_IRQ_DOMAIN_HIERARCHY is
    + * disabled. So we avoid an "#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY" here.
    + */
    + idata = irq_desc_get_irq_data(irq_data_to_desc(idata));
    +
    if (likely(!irqd_is_setaffinity_pending(idata)))
    return;

    --
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