On Tue, Apr 15, 2025 at 05:19:27PM -0700, Jakub Kicinski wrote:

On Tue, 15 Apr 2025 17:35:36 +0100 Simon Horman wrote:

quoted

quoted

@@ -1690,7 +1690,7 @@ static int __init ic_proto_name(char *name)
 			*v = 0;
 			if (kstrtou8(client_id, 0, dhcp_client_identifier))
 				pr_debug("DHCP: Invalid client identifier type\n");
-			strncpy(dhcp_client_identifier + 1, v + 1, 251);
+			strscpy(dhcp_client_identifier + 1, v + 1, 251);  

As an aside, I'm curious to know why the length is 251
rather than 252 (sizeof(dhcp_client_identifier) -1).
But that isn't strictly related to this patch.

Isn't this because strncpy() doesn't nul-terminate, and since this is a
static variable if we use len - 1 we guarantee that there will be a null
byte at the end? If we switch to strscpy we'll make the max string len
1 char shorter.

Yes, that makes sense to me.
And so I think the patch should also increase 251 to 252.