[PATCH] iio: adc: exynos-adc: Fix NULL pointer exception on unbind

From: Krzysztof Kozlowski
Date: Fri Feb 08 2019 - 18:39:38 EST

Fix NULL pointer exception on device unbind when device tree does not
contain "has-touchscreen" property. In such case the input device is
not registered so it should not be unregistered.

$ echo "12d10000.adc" > /sys/bus/platform/drivers/exynos-adc/unbind

Unable to handle kernel NULL pointer dereference at virtual address 00000474
(input_unregister_device) from [<c0772060>] (exynos_adc_remove+0x20/0x80)
(exynos_adc_remove) from [<c0587d5c>] (platform_drv_remove+0x20/0x40)
(platform_drv_remove) from [<c05860f0>] (device_release_driver_internal+0xdc/0x1ac)
(device_release_driver_internal) from [<c0583ecc>] (unbind_store+0x60/0xd4)
(unbind_store) from [<c031b89c>] (kernfs_fop_write+0x100/0x1e0)
(kernfs_fop_write) from [<c029709c>] (__vfs_write+0x2c/0x17c)
(__vfs_write) from [<c0297374>] (vfs_write+0xa4/0x184)
(vfs_write) from [<c0297594>] (ksys_write+0x4c/0xac)
(ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28)

Fixes: 2bb8ad9b44c5 ("iio: exynos-adc: add experimental touchscreen support")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
drivers/iio/adc/exynos_adc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
index fa2d2b5767f3..41da522fc673 100644
--- a/drivers/iio/adc/exynos_adc.c
+++ b/drivers/iio/adc/exynos_adc.c
@@ -929,7 +929,7 @@ static int exynos_adc_remove(struct platform_device *pdev)
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct exynos_adc *info = iio_priv(indio_dev);

+ if (IS_REACHABLE(CONFIG_INPUT) && info->input) {
free_irq(info->tsirq, info);