[PATCH 5.5 127/257] genirq/debugfs: Add missing sanity checks to interrupt injection

[Greg Kroah-Hartman]

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

commit a740a423c36932695b01a3e920f697bc55b05fec upstream.

Interrupts cannot be injected when the interrupt is not activated and when
a replay is already in progress.

Fixes: 536e2e34bd00 ("genirq/debugfs: Triggering of interrupts from userspace")
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Marc Zyngier <maz@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20200306130623.500019114@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/irq/debugfs.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/kernel/irq/debugfs.c
+++ b/kernel/irq/debugfs.c
@@ -206,8 +206,15 @@ static ssize_t irq_debug_write(struct fi
 		chip_bus_lock(desc);
 		raw_spin_lock_irqsave(&desc->lock, flags);
 
-		if (irq_settings_is_level(desc) || desc->istate & IRQS_NMI) {
-			/* Can't do level nor NMIs, sorry */
+		/*
+		 * Don't allow injection when the interrupt is:
+		 *  - Level or NMI type
+		 *  - not activated
+		 *  - replaying already
+		 */
+		if (irq_settings_is_level(desc) ||
+		    !irqd_is_activated(&desc->irq_data) ||
+		    (desc->istate & (IRQS_NMI | IRQS_REPLAY))) {
 			err = -EINVAL;
 		} else {
 			desc->istate |= IRQS_PENDING;