# \[PATCH 02/28\] sunrpc: Refactor rpc\_sockaddr2uaddr() to use snprintf() instead of strlcat()

- From: Bill Wendling \<morbo@google.com\>
- Date: 2026-09-15 08:19:55 
- List: linux-input
- Page: https://ratatoskr.run/linux-input/2026/09/17577949
- Thread: https://ratatoskr.run/loongarch/2026/09/17577947/t.md

```text
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: <redacted>
Assisted-by: CoPilot:3.5-sonnet [editor_update_file, shell_command_run]
Signed-off-by: Bill Wendling <morbo@google.com>
---
Cc: Russell King <linux@armlinux.org.uk>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Matthias Schwarzott <zzam@gentoo.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <redacted>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Arend van Spriel <arend.vanspriel@broadcom.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Peter Griffin <peter.griffin@linaro.org>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Linus Walleij <linusw@kernel.org>
Cc: Anil Gurumurthy <anil.gurumurthy@qlogic.com>
Cc: Sudarsana Kalluru <sudarsana.kalluru@qlogic.com>
Cc: "Martin K. Petersen" <mkp@kernel.org>
Cc: Trond Myklebust <trondmy@kernel.org>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Mike Marshall <hubcap@omnibond.com>
Cc: Martin Brandenburg <martin@omnibond.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Simon Horman <horms@kernel.org>
Cc: Chuck Lever <cel@kernel.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: NeilBrown <neil@brown.name>
Cc: Olga Kornievskaia <okorniev@redhat.com>
Cc: Dai Ngo <Dai.Ngo@oracle.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Cc: Kanglong Wang <redacted>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Qiang Ma <redacted>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Pengpeng Hou <redacted>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Breno Leitao <leitao@debian.org>
Cc: Thorsten Blum <blum@kernel.org>
Cc: Harshit Mogalapalli <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Ashutosh Desai <redacted>
Cc: Imre Deak <redacted>
Cc: Dmitry Baryshkov <redacted>
Cc: Johan Hovold <johan@kernel.org>
Cc: Johannes Berg <redacted>
Cc: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Cc: Alexander Stein <redacted>
Cc: Cryolitia PukNgae <cryolitia@uniontech.com>
Cc: Jiaming Zhang <redacted>
Cc: Will Porter <redacted>
Cc: Cen Zhang <redacted>
Cc: "Cássio Gabriel" <redacted>
Cc: Rong Zhang <i@rong.moe>
Cc: Arun Raghavan <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
---
 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

```