gpio: ml-ioh: Fix buffer underwrite on probe error path

Druidos · linusw · commit 4bf4eed44bfe · 2018-07-29T23:13:09.000+02:00
If ioh_gpio_probe() fails on devm_irq_alloc_descs() then chip may point
to any element of chip_save array, so reverse iteration from pointer chip
may become chip_save[-1] and gpiochip_remove() will operate with wrong
memory.

The patch fix the error path of ioh_gpio_probe() to correctly bypass
chip_save array.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev &lt;vasilyev@ispras.ru&gt;
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
diff --git a/drivers/gpio/gpio-ml-ioh.c b/drivers/gpio/gpio-ml-ioh.c
@@ -496,9 +496,10 @@ static int ioh_gpio_probe(struct pci_dev *pdev,
 	return 0;
 
 err_gpiochip_add:
+	chip = chip_save;
 	while (--i >= 0) {
-		chip--;
 		gpiochip_remove(&chip->gpio);
+		chip++;
 	}
 	kfree(chip_save);
 
