linux-kernel - [PATCH v2] NFS: Fix an off by one in root_nfs

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Message-ID: <fb121003ce56182477c693ad7adc37e4308e35aa.1708290887.git.christophe.jaillet@wanadoo.fr>
Date: Sun, 18 Feb 2024 22:16:53 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: bcodding@...hat.com,
	Trond Myklebust <trond.myklebust@...merspace.com>,
	Anna Schumaker <anna@...nel.org>,
	Chuck Lever <chuck.lever@...cle.com>
Cc: linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	linux-nfs@...r.kernel.org
Subject: [PATCH v2] NFS: Fix an off by one in root_nfs_cat()

The intent is to check if 'dest' is truncated or not. So, >= should be
used instead of >, because strlcat() returns the length of 'dest' and 'src'
excluding the trailing NULL.

Fixes: 56463e50d1fc ("NFS: Use super.c for NFSROOT mount option parsing")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Reviewed-by: Benjamin Coddington <bcodding@...hat.com>
---
v2: - Fix a typo in the commit message   [Benjamin Coddington]
    - Add R-b tag

v1: https://lore.kernel.org/all/856a652a7e28dde246b00025da7d4115978ae75f.1698184400.git.christophe.jaillet@wanadoo.fr/
---
 fs/nfs/nfsroot.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfsroot.c b/fs/nfs/nfsroot.c
index 7600100ba26f..432612d22437 100644
--- a/fs/nfs/nfsroot.c
+++ b/fs/nfs/nfsroot.c
@@ -175,10 +175,10 @@ static int __init root_nfs_cat(char *dest, const char *src,
 	size_t len = strlen(dest);
 
 	if (len && dest[len - 1] != ',')
-		if (strlcat(dest, ",", destlen) > destlen)
+		if (strlcat(dest, ",", destlen) >= destlen)
 			return -1;
 
-	if (strlcat(dest, src, destlen) > destlen)
+	if (strlcat(dest, src, destlen) >= destlen)
 		return -1;
 	return 0;
 }
-- 
2.43.2