linux-kernel - [PATCH 07/20] SUNRPC: Manual replacement of the deprecated strlcpy() with return values

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Message-Id: <20210222151231.22572-8-romain.perier@gmail.com>
Date:   Mon, 22 Feb 2021 16:12:18 +0100
From:   Romain Perier <romain.perier@...il.com>
To:     Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Chuck Lever <chuck.lever@...cle.com>
Cc:     Romain Perier <romain.perier@...il.com>, linux-nfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 07/20] SUNRPC: Manual replacement of the deprecated strlcpy() with return values

The strlcpy() reads the entire source buffer first, it is dangerous if
the source buffer lenght is unbounded or possibility non NULL-terminated.
It can lead to linear read overflows, crashes, etc...

As recommended in the deprecated interfaces [1], it should be replaced
by strscpy.

This commit replaces all calls to strlcpy that handle the return values
by the corresponding strscpy calls with new handling of the return
values (as it is quite different between the two functions).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy

Signed-off-by: Romain Perier <romain.perier@...il.com>
---
 net/sunrpc/clnt.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 612f0a641f4c..3c5c4ad8a808 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -282,7 +282,7 @@ static struct rpc_xprt *rpc_clnt_set_transport(struct rpc_clnt *clnt,
 
 static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename)
 {
-	clnt->cl_nodelen = strlcpy(clnt->cl_nodename,
+	clnt->cl_nodelen = strscpy(clnt->cl_nodename,
 			nodename, sizeof(clnt->cl_nodename));
 }
 
@@ -422,6 +422,10 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
 		nodename = utsname()->nodename;
 	/* save the nodename */
 	rpc_clnt_set_nodename(clnt, nodename);
+	if (clnt->cl_nodelen == -E2BIG) {
+		err = -ENOMEM;
+		goto out_no_path;
+	}
 
 	err = rpc_client_register(clnt, args->authflavor, args->client_name);
 	if (err)