netfilter: nft_osf: refactor deprecated strncpy

Use `strscpy_pad` over `strncpy` for NUL-terminated strings.

We can also drop the + 1 from `NFT_OSF_MAXGENRELEN + 1` since `strscpy`
will guarantee NUL-termination.
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

net/netfilter/nft_osf.c

@@ -23,7 +23,7 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
 	struct nft_osf *priv = nft_expr_priv(expr);
 	u32 *dest = &regs->data[priv->dreg];
 	struct sk_buff *skb = pkt->skb;
-	char os_match[NFT_OSF_MAXGENRELEN + 1];
+	char os_match[NFT_OSF_MAXGENRELEN];
 	const struct tcphdr *tcp;
 	struct nf_osf_data data;
 	struct tcphdr _tcph;
@@ -45,7 +45,7 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
 	}
 
 	if (!nf_osf_find(skb, nf_osf_fingers, priv->ttl, &data)) {
-		strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
+		strscpy_pad((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
 	} else {
 		if (priv->flags & NFT_OSF_F_VERSION)
 			snprintf(os_match, NFT_OSF_MAXGENRELEN, "%s:%s",
@@ -53,7 +53,7 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
 		else
 			strscpy(os_match, data.genre, NFT_OSF_MAXGENRELEN);
 
-		strncpy((char *)dest, os_match, NFT_OSF_MAXGENRELEN);
+		strscpy_pad((char *)dest, os_match, NFT_OSF_MAXGENRELEN);
 	}
 }