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.

Fixes: 52f518a3a7c 'x86/MSI: Use hierarchical irqdomains to manage MSI interrupts'
Reported-by: Huang Ying <ying.huang@intel.com>
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>

1 files changed, 8 insertions, 1 deletions

diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
index ca3f4aaff707..dd203e276b07 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;