linux-kernel - [PATCH] gpio: exar: Fix bad handling for ida_simple

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Date:   Wed, 29 Apr 2020 15:56:54 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Kangjie Lu <kjlu@....edu>, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] gpio: exar: Fix bad handling for ida_simple_get error path

The commit 7ecced0934e5 ("gpio: exar: add a check for the return value
of ida_simple_get fails") added a goto jump to the common error
handler for ida_simple_get() error, but this is wrong in two ways:
it doesn't set the proper return code and, more badly, it invokes
ida_simple_remove() with a negative index that shall lead to a kernel
panic via BUG_ON().

This patch addresses those two issues.

Fixes: 7ecced0934e5 ("gpio: exar: add a check for the return value of ida_simple_get fails")
Cc: <stable@...r.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 drivers/gpio/gpio-exar.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-exar.c b/drivers/gpio/gpio-exar.c
index da1ef0b1c291..b1accfba017d 100644
--- a/drivers/gpio/gpio-exar.c
+++ b/drivers/gpio/gpio-exar.c
@@ -148,8 +148,10 @@ static int gpio_exar_probe(struct platform_device *pdev)
 	mutex_init(&exar_gpio->lock);
 
 	index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
-	if (index < 0)
-		goto err_destroy;
+	if (index < 0) {
+		ret = index;
+		goto err_mutex_destroy;
+	}
 
 	sprintf(exar_gpio->name, "exar_gpio%d", index);
 	exar_gpio->gpio_chip.label = exar_gpio->name;
@@ -176,6 +178,7 @@ static int gpio_exar_probe(struct platform_device *pdev)
 
 err_destroy:
 	ida_simple_remove(&ida_index, index);
+err_mutex_destroy:
 	mutex_destroy(&exar_gpio->lock);
 	return ret;
 }
-- 
2.16.4