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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Anton Vasilyev <vasilyev@ispras.ru>,
        Linus Walleij <linus.walleij@linaro.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 078/131] gpio: ml-ioh: Fix buffer underwrite on
 probe error path
Thread-Topic: [PATCH AUTOSEL 4.18 078/131] gpio: ml-ioh: Fix buffer underwrite
 on probe error path
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Date:   Sun, 2 Sep 2018 13:04:43 +0000
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From: Anton Vasilyev <vasilyev@ispras.ru>

[ Upstream commit 4bf4eed44bfe288f459496eaf38089502ef91a79 ]

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>
---
 drivers/gpio/gpio-ml-ioh.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-ml-ioh.c b/drivers/gpio/gpio-ml-ioh.c
index b23d9a36be1f..51c7d1b84c2e 100644
--- 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;
=20
 err_gpiochip_add:
+	chip =3D chip_save;
 	while (--i >=3D 0) {
-		chip--;
 		gpiochip_remove(&chip->gpio);
+		chip++;
 	}
 	kfree(chip_save);
=20
--=20
2.17.1