usb: dwc3: st: fix probed platform device ref count on probe error path

commit ddfcfeb upstream.

The probe function never performs any paltform device allocation, thus
error path "undo_platform_dev_alloc" is entirely bogus.  It drops the
reference count from the platform device being probed.  If error path is
triggered, this will lead to unbalanced device reference counts and
premature release of device resources, thus possible use-after-free when
releasing remaining devm-managed resources.

Fixes: f83fca0 ("usb: dwc3: add ST dwc3 glue layer to manage dwc3 HC")
Cc: [email protected]
Signed-off-by: Krzysztof Kozlowski <[email protected]>
Acked-by: Thinh Nguyen <[email protected]>
Reviewed-by: Patrice Chotard <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/usb/dwc3/dwc3-st.c

@@ -219,10 +219,8 @@ static int st_dwc3_probe(struct platform_device *pdev)
 	dwc3_data->regmap = regmap;
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "syscfg-reg");
-	if (!res) {
-		ret = -ENXIO;
-		goto undo_platform_dev_alloc;
-	}
+	if (!res)
+		return -ENXIO;
 
 	dwc3_data->syscfg_reg_off = res->start;
 
@@ -233,8 +231,7 @@ static int st_dwc3_probe(struct platform_device *pdev)
 		devm_reset_control_get_exclusive(dev, "powerdown");
 	if (IS_ERR(dwc3_data->rstc_pwrdn)) {
 		dev_err(&pdev->dev, "could not get power controller\n");
-		ret = PTR_ERR(dwc3_data->rstc_pwrdn);
-		goto undo_platform_dev_alloc;
+		return PTR_ERR(dwc3_data->rstc_pwrdn);
 	}
 
 	/* Manage PowerDown */
@@ -296,8 +293,6 @@ static int st_dwc3_probe(struct platform_device *pdev)
 	reset_control_assert(dwc3_data->rstc_rst);
 undo_powerdown:
 	reset_control_assert(dwc3_data->rstc_pwrdn);
-undo_platform_dev_alloc:
-	platform_device_put(pdev);
 	return ret;
 }