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Date: Sat, 24 Aug 2013 13:48:28 -0500 From: danielfsantos@....net To: Linus Walleij <linus.walleij@...aro.org>, linux-gpio@...r.kernel.org, LKML <linux-kernel@...r.kernel.org> Cc: Daniel Santos <daniel.santos@...ox.com> Subject: [PATCH] gpiolib: Fix crash when exporting non-existant gpio I got this on an RPi and I can't find anything specific to that. Besides, it's clearly wrong to try to access desc->chip when we have just tested that it may be NULL at drivers/gpio/gpiolib.c:1409: chip = desc->chip; if (chip == NULL) goto done; .... done: if (status) pr_debug("_gpio_request: gpio-%d (%s) status %d\n", desc_to_gpio(desc), label ? : "?", status); To reproduce, just pick an invalid gpio nubmer and: echo -n 248 > /sys/class/gpio/export However, I wasn't able to reproduce it on my laptop, maybe because I don't have any real gpio chips there, not sure. More info on RPi bug report: https://github.com/raspberrypi/linux/issues/364 [ 222.961384] Unable to handle kernel NULL pointer dereference at virtual address 00000044 [ 222.969486] pgd = d97d0000 [ 222.972190] [00000044] *pgd=1aaca831, *pte=00000000, *ppte=00000000 [ 222.978483] Internal error: Oops: 17 [#1] PREEMPT ARM --- drivers/gpio/gpiolib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index d6413b2..e547f75f8b 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -136,7 +136,7 @@ static struct gpio_desc *gpio_to_desc(unsigned gpio) */ static int desc_to_gpio(const struct gpio_desc *desc) { - return desc->chip->base + gpio_chip_hwgpio(desc); + return desc->chip ? desc->chip->base + gpio_chip_hwgpio(desc) : -1; } -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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