If a button device fails to probe, it will still be added to the uclass device list, and therefore will still be iterated over in button_read_keys() resulting in a UAF on the buttons private data.

Resolve this by unbinding button devices that aren't active after probing, and print a warning so it's clear that the button is broken.

Fixes: e8779962898e ("dm: input: add button_kbd driver") Signed-off-by: Caleb Connolly caleb.connolly@linaro.org --- drivers/input/button_kbd.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/input/button_kbd.c b/drivers/input/button_kbd.c index 74fadfca8bb8..c73d3b18be9c 100644 --- a/drivers/input/button_kbd.c +++ b/drivers/input/button_kbd.c @@ -33,9 +33,10 @@ struct button_kbd_priv { static int button_kbd_start(struct udevice *dev) { struct button_kbd_priv *priv = dev_get_priv(dev); int i = 0; - struct udevice *button_gpio_devp; + struct udevice *button_gpio_devp, *next_devp; + struct uclass *uc;

uclass_foreach_dev_probe(UCLASS_BUTTON, button_gpio_devp) { struct button_uc_plat *uc_plat = dev_get_uclass_plat(button_gpio_devp); /* Ignore the top-level button node */ @@ -45,8 +46,23 @@ static int button_kbd_start(struct udevice *dev) uc_plat->label, i, button_gpio_devp->name); i++; }

+ if (uclass_get(UCLASS_BUTTON, &uc)) + return -ENOENT; + + /* + * Unbind any buttons that failed to probe so we don't iterate over + * them when polling. + */ + uclass_foreach_dev_safe(button_gpio_devp, next_devp, uc) { + if (!(dev_get_flags(button_gpio_devp) & DM_FLAG_ACTIVATED)) { + log_warning("Button %s failed to probe\n", + button_gpio_devp->name); + device_unbind(button_gpio_devp); + } + } + priv->button_size = i; priv->old_state = calloc(i, sizeof(int));

return 0;