From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 11 May 2017 11:54:11 +0000 (+0200)
Subject: genirq: Fix chained interrupt data ordering
X-Git-Tag: v4.12-rc2~5^2
X-Git-Url: http://git.samba.org/samba.git/?p=sfrench%2Fcifs-2.6.git;a=commitdiff_plain;h=2c4569ca26986d18243f282dd727da27e9adae4c

genirq: Fix chained interrupt data ordering

irq_set_chained_handler_and_data() sets up the chained interrupt and then
stores the handler data.

That's racy against an immediate interrupt which gets handled before the
store of the handler data happened. The handler will dereference a NULL
pointer and crash.

Cure it by storing handler data before installing the chained handler.

Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
---

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 686be4b73018..c94da688ee9b 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -880,8 +880,8 @@ irq_set_chained_handler_and_data(unsigned int irq, irq_flow_handler_t handle,
 	if (!desc)
 		return;
 
-	__irq_do_set_handler(desc, handle, 1, NULL);
 	desc->irq_common_data.handler_data = data;
+	__irq_do_set_handler(desc, handle, 1, NULL);
 
 	irq_put_desc_busunlock(desc, flags);
 }