linux-kernel - [PATCH] net: sunrpc: Fix an off by one in root_nfs

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Date:   Tue, 24 Oct 2023 23:55:30 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     chuck.lever@...cle.com, jlayton@...nel.org, neilb@...e.de,
        kolga@...app.com, Dai.Ngo@...cle.com, tom@...pey.com,
        trond.myklebust@...merspace.com, anna@...nel.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com
Cc:     linux-nfs@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] net: sunrpc: Fix an off by one in root_nfs_cat()

The intent is to check if the strings' are truncated or not. So, >= should
be used instead of >, because strlcat() and snprintf() return the length of
the output, excluding the trailing NULL.

Fixes: a02d69261134 ("SUNRPC: Provide functions for managing universal addresses")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 net/sunrpc/addr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/addr.c b/net/sunrpc/addr.c
index d435bffc6199..97ff11973c49 100644
--- a/net/sunrpc/addr.c
+++ b/net/sunrpc/addr.c
@@ -284,10 +284,10 @@ char *rpc_sockaddr2uaddr(const struct sockaddr *sap, gfp_t gfp_flags)
 	}
 
 	if (snprintf(portbuf, sizeof(portbuf),
-		     ".%u.%u", port >> 8, port & 0xff) > (int)sizeof(portbuf))
+		     ".%u.%u", port >> 8, port & 0xff) >= (int)sizeof(portbuf))
 		return NULL;
 
-	if (strlcat(addrbuf, portbuf, sizeof(addrbuf)) > sizeof(addrbuf))
+	if (strlcat(addrbuf, portbuf, sizeof(addrbuf)) >= sizeof(addrbuf))
 		return NULL;
 
 	return kstrdup(addrbuf, gfp_flags);
-- 
2.32.0