[PATCH 02/28] sunrpc: Refactor rpc_sockaddr2uaddr() to use snprintf() instead of strlcat()

[Bill Wendling]

rpc_sockaddr2uaddr() formats the IP address into "addrbuf", formats the
port into a temporary "portbuf" buffer with snprintf(), and then appends
"portbuf" to "addrbuf" using strlcat().

In preparation for removing the deprecated strlcat() API[1], capture the
length returned by rpc_ntop4() and rpc_ntop6_noscopeid() and format the
port directly onto the end of "addrbuf" with snprintf(). This eliminates
the strlcat() call and the temporary "portbuf" buffer.

Link: https://github.com/KSPP/linux/issues/370 [1]
Cc: codemender-patching+linux@xxxxxxxxxx
Assisted-by: CoPilot:3.5-sonnet [editor_update_file, shell_command_run]
Signed-off-by: Bill Wendling <morbo@xxxxxxxxxx>
---
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
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---
 net/sunrpc/addr.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/sunrpc/addr.c b/net/sunrpc/addr.c
index 97ff11973c49..a1e4173e5a53 100644
--- a/net/sunrpc/addr.c
+++ b/net/sunrpc/addr.c
@@ -264,18 +264,20 @@ EXPORT_SYMBOL_GPL(rpc_pton);
  */
 char *rpc_sockaddr2uaddr(const struct sockaddr *sap, gfp_t gfp_flags)
 {
-	char portbuf[RPCBIND_MAXUADDRPLEN];
 	char addrbuf[RPCBIND_MAXUADDRLEN];
 	unsigned short port;
+	size_t len;
 
 	switch (sap->sa_family) {
 	case AF_INET:
-		if (rpc_ntop4(sap, addrbuf, sizeof(addrbuf)) == 0)
+		len = rpc_ntop4(sap, addrbuf, sizeof(addrbuf));
+		if (len == 0 || len >= sizeof(addrbuf))
 			return NULL;
 		port = ntohs(((struct sockaddr_in *)sap)->sin_port);
 		break;
 	case AF_INET6:
-		if (rpc_ntop6_noscopeid(sap, addrbuf, sizeof(addrbuf)) == 0)
+		len = rpc_ntop6_noscopeid(sap, addrbuf, sizeof(addrbuf));
+		if (len == 0 || len >= sizeof(addrbuf))
 			return NULL;
 		port = ntohs(((struct sockaddr_in6 *)sap)->sin6_port);
 		break;
@@ -283,11 +285,8 @@ char *rpc_sockaddr2uaddr(const struct sockaddr *sap, gfp_t gfp_flags)
 		return NULL;
 	}
 
-	if (snprintf(portbuf, sizeof(portbuf),
-		     ".%u.%u", port >> 8, port & 0xff) >= (int)sizeof(portbuf))
-		return NULL;
-
-	if (strlcat(addrbuf, portbuf, sizeof(addrbuf)) >= sizeof(addrbuf))
+	if (snprintf(addrbuf + len, sizeof(addrbuf) - len,
+		     ".%u.%u", port >> 8, port & 0xff) >= sizeof(addrbuf) - len)
 		return NULL;
 
 	return kstrdup(addrbuf, gfp_flags);
@@ -352,3 +351,4 @@ size_t rpc_uaddr2sockaddr(struct net *net, const char *uaddr,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(rpc_uaddr2sockaddr);
+
-- 
2.55.0.1032.g73a4cd73de-goog