Commit 92ea7727 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Fix crash with irqpoll due to the IRQF_IRQPOLL flag testing 



With irqpoll enabled, trying to test the IRQF_IRQPOLL flag in the
actions would cause a NULL pointer dereference if no action was
installed (for example, the driver might have been unloaded with
interrupts still pending).

So be a bit more careful about testing the flag by making sure to test
for that case.

(The actual _change_ is trivial, the patch is more than a one-liner
because I rewrote the testing to also be much more readable.

Original (discarded) bugfix by Bernhard Walle.

Cc: Bernhard Walle <bwalle@suse.de>
Tested-by: default avatarVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent db2668fd

kernel/irq/spurious.c

+37 −9
Original line number Diff line number Diff line
@@ -135,6 +135,39 @@ report_bad_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret) 
	}

}



static inline int try_misrouted_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret)

{

	struct irqaction *action;



	if (!irqfixup)

		return 0;



	/* We didn't actually handle the IRQ - see if it was misrouted? */

	if (action_ret == IRQ_NONE)

		return 1;



	/*

	 * But for 'irqfixup == 2' we also do it for handled interrupts if

	 * they are marked as IRQF_IRQPOLL (or for irq zero, which is the

	 * traditional PC timer interrupt.. Legacy)

	 */

	if (irqfixup < 2)

		return 0;



	if (!irq)

		return 1;



	/*

	 * Since we don't get the descriptor lock, "action" can

	 * change under us.  We don't really care, but we don't

	 * want to follow a NULL pointer. So tell the compiler to

	 * just load it once by using a barrier.

	 */

	action = desc->action;

	barrier();

	return action && (action->flags & IRQF_IRQPOLL);

}



void note_interrupt(unsigned int irq, struct irq_desc *desc,

		    irqreturn_t action_ret)

{
@@ -144,16 +177,11 @@ void note_interrupt(unsigned int irq, struct irq_desc *desc, 
			report_bad_irq(irq, desc, action_ret);

	}



	if (unlikely(irqfixup)) {

		/* Don't punish working computers */

		if ((irqfixup == 2 && ((irq == 0) ||

				(desc->action->flags & IRQF_IRQPOLL))) ||

				action_ret == IRQ_NONE) {

	if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {

		int ok = misrouted_irq(irq);

		if (action_ret == IRQ_NONE)

			desc->irqs_unhandled -= ok;

	}

	}



	desc->irq_count++;

	if (likely(desc->irq_count < 100000))

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