gpiolib: Fix NULL pointer deference

Orabug: 25256944

[ Upstream commit 11f33a6d15bfa397867ac0d7f3481b6dd683286f ]

Under some circumstances, a gpiochip might be half cleaned from the
gpio_device list.

This patch makes sure that the chip pointer is still valid, before
calling the match function.

[  104.088296] BUG: unable to handle kernel NULL pointer dereference at
0000000000000090
[  104.089772] IP: [<ffffffff813d2045>] of_gpiochip_find_and_xlate+0x15/0x80
[  104.128273] Call Trace:
[  104.129802]  [<ffffffff813d2030>] ? of_parse_own_gpio+0x1f0/0x1f0
[  104.131353]  [<ffffffff813cd910>] gpiochip_find+0x60/0x90
[  104.132868]  [<ffffffff813d21ba>] of_get_named_gpiod_flags+0x9a/0x120
...
[  104.141586]  [<ffffffff8163d12b>] gpio_led_probe+0x11b/0x360

Cc: stable@vger.kernel.org
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 796795362c839447eadc671420f8c4bdd1deb182)
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 6bc612b8a49fcf859261173e00d0e7389d7d2b05..95752d38b7fe92b772335955177e37976d6a8a7c 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -375,7 +375,7 @@ struct gpio_chip *gpiochip_find(void *data,
 
        spin_lock_irqsave(&gpio_lock, flags);
        list_for_each_entry(chip, &gpio_chips, list)
-               if (match(chip, data))
+               if (chip && match(chip, data))
                        break;
 
        /* No match? */