gpio: pca953x: Survive spurious interrupts

The pca953x driver never checks the result of irq_find_mapping(),
which returns 0 when no mapping is found. When a spurious interrupt
is delivered (which can happen under obscure circumstances), the
kernel explodes as it still tries to handle the error code as
a real interrupt.

Handle this particular case and warn on spurious interrupts.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201005140217.1390851-1-maz@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index fb61f2fc6ed7cf6f24cda79cd5484efa8587cf67..c2d6121c48c9bce7af4b83f3be287219c2b014c4 100644 (file)
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -824,8 +824,21 @@ static irqreturn_t pca953x_irq_handler(int irq, void *devid)
        ret = pca953x_irq_pending(chip, pending);
        mutex_unlock(&chip->i2c_lock);
 
-       for_each_set_bit(level, pending, gc->ngpio)
-               handle_nested_irq(irq_find_mapping(gc->irq.domain, level));
+       if (ret) {
+               ret = 0;
+
+               for_each_set_bit(level, pending, gc->ngpio) {
+                       int nested_irq = irq_find_mapping(gc->irq.domain, level);
+
+                       if (unlikely(nested_irq <= 0)) {
+                               dev_warn_ratelimited(gc->parent, "unmapped interrupt %d\n", level);
+                               continue;
+                       }
+
+                       handle_nested_irq(nested_irq);
+                       ret = 1;
+               }
+       }
 
        return IRQ_RETVAL(ret);
 }