pinctrl: pinconf-generic: Fully validate 'pinmux' property

[ Upstream commit c98324e ]

The pinconf_generic_parse_dt_pinmux() assumes that the 'pinmux' property
is not empty when present. This might be not true. With that, the allocator
will give a special value in return and not NULL which lead to the crash
when trying to access that (invalid) memory. Fix that by fully validating
'pinmux' value, including its length.

Fixes: 7112c05 ("pinctrl: pinconf-generic: Add API for pinmux propertity in DTS file")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: andy-shev

drivers/pinctrl/pinconf-generic.c

@@ -261,12 +261,17 @@ int pinconf_generic_parse_dt_pinmux(struct device_node *np, struct device *dev,
 		return -ENOENT;
 	}
 
+	npins_t = prop->length / sizeof(u32);
+	if (npins_t == 0) {
+		dev_info(dev, "pinmux property doesn't have entries\n");
+		return -ENODATA;
+	}
+
 	if (!pid || !pmux || !npins) {
 		dev_err(dev, "parameters error\n");
 		return -EINVAL;
 	}
 
-	npins_t = prop->length / sizeof(u32);
 	pid_t = devm_kcalloc(dev, npins_t, sizeof(*pid_t), GFP_KERNEL);
 	pmux_t = devm_kcalloc(dev, npins_t, sizeof(*pmux_t), GFP_KERNEL);
 	if (!pid_t || !pmux_t) {