[PATCH net-next v2] net: usb: pegasus: replace simple_strtoul with kstrtouint

[Sajal Gupta <sajal2005gupta@gmail.com>]

simple_strtoul() is deprecated as it has no error checking. Replace it
with kstrtouint() which returns an error code on invalid input, and add
appropriate error handling.

Also add a NULL check before parsing flags, since strsep() can set id
to NULL if the input has fewer tokens than expected.

Preserve the original behavior for a trailing colon by checking *id
before parsing flags, so an empty string results in flags = 0 rather
than an error.

Signed-off-by: Sajal Gupta <sajal2005gupta@gmail.com>
---
Changes in v2:
 - Drop err variable
 - Preserve original behavior for trailing colon by checking *id
   before parsing flags
v1: https://lore.kernel.org/netdev/20260506152653.52329-1-sajal2005gupta@gmail.com/

 drivers/net/usb/pegasus.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
index db85f40734d7..8700eeb8e22d 100644
--- a/drivers/net/usb/pegasus.c
+++ b/drivers/net/usb/pegasus.c
@@ -1328,14 +1328,18 @@ static void __init parse_id(char *id)
 	unsigned int vendor_id = 0, device_id = 0, flags = 0, i = 0;
 	char *token, *name = NULL;
 
-	if ((token = strsep(&id, ":")) != NULL)
+	token = strsep(&id, ":");
+	if (token)
 		name = token;
 	/* name now points to a null terminated string*/
-	if ((token = strsep(&id, ":")) != NULL)
-		vendor_id = simple_strtoul(token, NULL, 16);
-	if ((token = strsep(&id, ":")) != NULL)
-		device_id = simple_strtoul(token, NULL, 16);
-	flags = simple_strtoul(id, NULL, 16);
+	token = strsep(&id, ":");
+	if (token && kstrtouint(token, 16, &vendor_id))
+		return;
+	token = strsep(&id, ":");
+	if (token && kstrtouint(token, 16, &device_id))
+		return;
+	if (id && *id && kstrtouint(id, 16, &flags))
+		return;
 	pr_info("%s: new device %s, vendor ID 0x%04x, device ID 0x%04x, flags: 0x%x\n",
 		driver_name, name, vendor_id, device_id, flags);
 
-- 
2.54.0