[tip:x86/urgent] x86/ioapic: Pass the correct data to unmask_ioapic_irq()

[tip-bot for Seunghun Han <tipbot@zytor.com>]

Commit-ID:  afabde6986911394c95c596f96d2ac833eef04cc
Gitweb:     http://git.kernel.org/tip/afabde6986911394c95c596f96d2ac833eef04cc
Author:     Seunghun Han <kkamagui@gmail.com>
AuthorDate: Tue, 18 Jul 2017 18:20:44 +0900
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 18 Jul 2017 17:39:54 +0200

x86/ioapic: Pass the correct data to unmask_ioapic_irq()

One of the rarely executed code pathes in check_timer() calls
unmask_ioapic_irq() passing irq_get_chip_data(0) as argument.

That's wrong as unmask_ioapic_irq() expects a pointer to the irq data of
interrupt 0. irq_get_chip_data(0) returns NULL, so the following
dereference in unmask_ioapic_irq() causes a kernel panic.

The issue went unnoticed in the first place because irq_get_chip_data()
returns a void pointer so the compiler cannot do a type check on the
argument. The code path was added for machines with broken configuration,
but it seems that those machines are either not running current kernels or
simply do not longer exist.

Hand in irq_get_irq_data(0) as argument which provides the correct data.

[ tglx: Rewrote changelog ]

Fixes: 4467715a44cc ("x86/irq: Move irq_cfg.irq_2_pin into io_apic.c")
Signed-off-by: Seunghun Han <kkamagui@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1500369644-45767-1-git-send-email-kkamagui@gmail.com

---
 arch/x86/kernel/apic/io_apic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index b4f5f73..237e9c2 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2093,7 +2093,7 @@ static inline void __init check_timer(void)
 			int idx;
 			idx = find_irq_entry(apic1, pin1, mp_INT);
 			if (idx != -1 && irq_trigger(idx))
-				unmask_ioapic_irq(irq_get_chip_data(0));
+				unmask_ioapic_irq(irq_get_irq_data(0));
 		}
 		irq_domain_deactivate_irq(irq_data);
 		irq_domain_activate_irq(irq_data);