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From:   Geert Uytterhoeven <geert+renesas@glider.be>
To:     Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc:     Benoit Parrot <bparrot@ti.com>,
        Laxman Dewangan <ldewangan@nvidia.com>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 2/3] gpio: Fix gpiochip_add_data_with_key() error path
Date:   Thu, 28 Mar 2019 14:13:48 +0100
Message-Id: <20190328131349.18838-3-geert+renesas@glider.be>
In-Reply-To: <20190328131349.18838-1-geert+renesas@glider.be>
References: <20190328131349.18838-1-geert+renesas@glider.be>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The err_remove_chip block is too coarse, and may perform cleanup that
must not be done.  E.g. if of_gpiochip_add() fails, of_gpiochip_remove()
is still called, causing:

    OF: ERROR: Bad of_node_put() on /soc/gpio@e6050000
    CPU: 1 PID: 20 Comm: kworker/1:1 Not tainted 5.1.0-rc2-koelsch+ #407
    Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
    Workqueue: events deferred_probe_work_func
    [<c020ec74>] (unwind_backtrace) from [<c020ae58>] (show_stack+0x10/0x14)
    [<c020ae58>] (show_stack) from [<c07c1224>] (dump_stack+0x7c/0x9c)
    [<c07c1224>] (dump_stack) from [<c07c5a80>] (kobject_put+0x94/0xbc)
    [<c07c5a80>] (kobject_put) from [<c0470420>] (gpiochip_add_data_with_key+0x8d8/0xa3c)
    [<c0470420>] (gpiochip_add_data_with_key) from [<c0473738>] (gpio_rcar_probe+0x1d4/0x314)
    [<c0473738>] (gpio_rcar_probe) from [<c052fca8>] (platform_drv_probe+0x48/0x94)

and later, if a GPIO consumer tries to use a GPIO from a failed
controller:

    WARNING: CPU: 0 PID: 1 at lib/refcount.c:156 kobject_get+0x38/0x4c
    refcount_t: increment on 0; use-after-free.
    Modules linked in:
    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.1.0-rc2-koelsch+ #407
    Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
    [<c020ec74>] (unwind_backtrace) from [<c020ae58>] (show_stack+0x10/0x14)
    [<c020ae58>] (show_stack) from [<c07c1224>] (dump_stack+0x7c/0x9c)
    [<c07c1224>] (dump_stack) from [<c0221580>] (__warn+0xd0/0xec)
    [<c0221580>] (__warn) from [<c02215e0>] (warn_slowpath_fmt+0x44/0x6c)
    [<c02215e0>] (warn_slowpath_fmt) from [<c07c58fc>] (kobject_get+0x38/0x4c)
    [<c07c58fc>] (kobject_get) from [<c068b3ec>] (of_node_get+0x14/0x1c)
    [<c068b3ec>] (of_node_get) from [<c0686f24>] (of_find_node_by_phandle+0xc0/0xf0)
    [<c0686f24>] (of_find_node_by_phandle) from [<c0686fbc>] (of_phandle_iterator_next+0x68/0x154)
    [<c0686fbc>] (of_phandle_iterator_next) from [<c0687fe4>] (__of_parse_phandle_with_args+0x40/0xd0)
    [<c0687fe4>] (__of_parse_phandle_with_args) from [<c0688204>] (of_parse_phandle_with_args_map+0x100/0x3ac)
    [<c0688204>] (of_parse_phandle_with_args_map) from [<c0471240>] (of_get_named_gpiod_flags+0x38/0x380)
    [<c0471240>] (of_get_named_gpiod_flags) from [<c046f864>] (gpiod_get_from_of_node+0x24/0xd8)
    [<c046f864>] (gpiod_get_from_of_node) from [<c0470aa4>] (devm_fwnode_get_index_gpiod_from_child+0xa0/0x144)
    [<c0470aa4>] (devm_fwnode_get_index_gpiod_from_child) from [<c05f425c>] (gpio_keys_probe+0x418/0x7bc)
    [<c05f425c>] (gpio_keys_probe) from [<c052fca8>] (platform_drv_probe+0x48/0x94)

Fix this by splitting the cleanup block, and adding a missing call to
gpiochip_irqchip_remove().

Fixes: 28355f81969962cf ("gpio: defer probe if pinctrl cannot be found")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
I'm not so sure about the need for the call to
gpiochip_irqchip_remove(), as add/remove are not really symmetrical.
Any comments?
---
 drivers/gpio/gpiolib.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 144af07335815998..ed4da07effe0ac40 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1379,7 +1379,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 
 	status = gpiochip_add_irqchip(chip, lock_key, request_key);
 	if (status)
-		goto err_remove_chip;
+		goto err_free_irqchip_mask;
 
 	status = of_gpiochip_add(chip);
 	if (status)
@@ -1387,7 +1387,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 
 	status = gpiochip_init_valid_mask(chip);
 	if (status)
-		goto err_remove_chip;
+		goto err_remove_of_chip;
 
 	for (i = 0; i < chip->ngpio; i++) {
 		struct gpio_desc *desc = &gdev->descs[i];
@@ -1415,14 +1415,18 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	if (gpiolib_initialized) {
 		status = gpiochip_setup_dev(gdev);
 		if (status)
-			goto err_remove_chip;
+			goto err_remove_acpi_chip;
 	}
 	return 0;
 
-err_remove_chip:
+err_remove_acpi_chip:
 	acpi_gpiochip_remove(chip);
+err_remove_of_chip:
 	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
+err_remove_chip:
+	gpiochip_irqchip_remove(chip);
+err_free_irqchip_mask:
 	gpiochip_free_valid_mask(chip);
 err_remove_irqchip_mask:
 	gpiochip_irqchip_free_valid_mask(chip);
-- 
2.17.1