PNP: ACPI: replace deprecated strncpy() with strscpy()

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We know dev->name should be NUL-terminated based on the presence of a
manual NUL-byte assignment.

NUL-padding is not required as dev is already zero-allocated which
renders any further NUL-byte assignments redundant:
dev = pnp_alloc_dev(&pnpacpi_protocol, num, pnpid); --->
  dev = kzalloc(sizeof(struct pnp_dev), GFP_KERNEL);

Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding. This simplifies the code and makes
the intent/behavior more obvious.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: KSPP/linux#90
Signed-off-by: Justin Stitt <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: JustinStitt

drivers/pnp/pnpacpi/core.c

@@ -250,12 +250,9 @@ static int __init pnpacpi_add_device(struct acpi_device *device)
 		dev->capabilities |= PNP_DISABLE;
 
 	if (strlen(acpi_device_name(device)))
-		strncpy(dev->name, acpi_device_name(device), sizeof(dev->name));
+		strscpy(dev->name, acpi_device_name(device), sizeof(dev->name));
 	else
-		strncpy(dev->name, acpi_device_bid(device), sizeof(dev->name));
-
-	/* Handle possible string truncation */
-	dev->name[sizeof(dev->name) - 1] = '\0';
+		strscpy(dev->name, acpi_device_bid(device), sizeof(dev->name));
 
 	if (dev->active)
 		pnpacpi_parse_allocated_resource(dev);