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

BugLink: https://bugs.launchpad.net/bugs/1798539

[ Upstream commit 4bf4eed4 ]

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 <vasilyev@ispras.ru>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/gpio/gpio-ml-ioh.c

@@ -495,9 +495,10 @@ static int ioh_gpio_probe(struct pci_dev *pdev,
 
 	chip = chip_save;
 err_gpiochip_add:
+	chip = chip_save;
 	while (--i >= 0) {
-		chip--;
 		gpiochip_remove(&chip->gpio);
+		chip++;
 	}
 	kfree(chip_save);