Input: mtk-pmic-keys - fix possible null pointer dereference

BugLink: https://bugs.launchpad.net/bugs/2115252

commit 11cdb50 upstream.

In mtk_pmic_keys_probe, the regs parameter is only set if the button is
parsed in the device tree. However, on hardware where the button is left
floating, that node will most likely be removed not to enable that
input. In that case the code will try to dereference a null pointer.

Let's use the regs struct instead as it is defined for all supported
platforms. Note that it is ok setting the key reg even if that latter is
disabled as the interrupt won't be enabled anyway.

Fixes: b581acb ("Input: mtk-pmic-keys - transfer per-key bit in mtk_pmic_keys_regs")
Signed-off-by: Gary Bisson <bisson.gary@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CVE-2025-37972
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: gibsson

drivers/input/keyboard/mtk-pmic-keys.c

@@ -147,8 +147,8 @@ static void mtk_pmic_keys_lp_reset_setup(struct mtk_pmic_keys *keys,
 	u32 value, mask;
 	int error;
 
-	kregs_home = keys->keys[MTK_PMIC_HOMEKEY_INDEX].regs;
-	kregs_pwr = keys->keys[MTK_PMIC_PWRKEY_INDEX].regs;
+	kregs_home = &regs->keys_regs[MTK_PMIC_HOMEKEY_INDEX];
+	kregs_pwr = &regs->keys_regs[MTK_PMIC_PWRKEY_INDEX];
 
 	error = of_property_read_u32(keys->dev->of_node, "power-off-time-sec",
 				     &long_press_debounce);