[tip:x86/apic] genirq: Prevent crash in irq_move_irq()

[tip-bot for Jiang Liu]

Commit-ID:  458526ec81d755dfaa17f3d863302afe6fbefca0
Gitweb:     http://git.kernel.org/tip/458526ec81d755dfaa17f3d863302afe6fbefca0
Author:     Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
AuthorDate: Mon, 1 Jun 2015 16:05:11 +0800
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 16 Jun 2015 09:23:28 +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.

Fixes: 52f518a3a7c 'x86/MSI: Use hierarchical irqdomains to manage MSI interrupts'
Reported-by: Huang Ying <ying.huang@xxxxxxxxx>
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1433145945-789-3-git-send-email-jiang.liu@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 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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