netdev - [PATCH] SUNRPC: Replace strlcpy with strscpy

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Date: Tue, 13 Jun 2023 00:40:54 +0000
From: Azeem Shaikh <azeemshaikh38@...il.com>
To: Chuck Lever <chuck.lever@...cle.com>,
	Jeff Layton <jlayton@...nel.org>
Cc: linux-hardening@...r.kernel.org,
	Azeem Shaikh <azeemshaikh38@...il.com>,
	Neil Brown <neilb@...e.de>,
	Olga Kornievskaia <kolga@...app.com>,
	Dai Ngo <Dai.Ngo@...cle.com>,
	Tom Talpey <tom@...pey.com>,
	linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Trond Myklebust <trond.myklebust@...merspace.com>,
	Anna Schumaker <anna@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org
Subject: [PATCH] SUNRPC: Replace strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since the getter in kernel_params_ops
handles -errorno return [3].

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
[3] https://elixir.bootlin.com/linux/v6.4-rc6/source/include/linux/moduleparam.h#L52

Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
---
 net/sunrpc/svc.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index e6d4cec61e47..e5f379c4fdb3 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -109,13 +109,13 @@ param_get_pool_mode(char *buf, const struct kernel_param *kp)
 	switch (*ip)
 	{
 	case SVC_POOL_AUTO:
-		return strlcpy(buf, "auto\n", 20);
+		return strscpy(buf, "auto\n", 20);
 	case SVC_POOL_GLOBAL:
-		return strlcpy(buf, "global\n", 20);
+		return strscpy(buf, "global\n", 20);
 	case SVC_POOL_PERCPU:
-		return strlcpy(buf, "percpu\n", 20);
+		return strscpy(buf, "percpu\n", 20);
 	case SVC_POOL_PERNODE:
-		return strlcpy(buf, "pernode\n", 20);
+		return strscpy(buf, "pernode\n", 20);
 	default:
 		return sprintf(buf, "%d\n", *ip);
 	}
-- 
2.41.0.162.gfafddb0af9-goog