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

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Message-Id: <7f97bb62c4e8137c5d7f7a7a30789440a5102b3f.1698183837.git.christophe.jaillet@wanadoo.fr>
Date:   Tue, 24 Oct 2023 23:47:42 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     trond.myklebust@...merspace.com, anna@...nel.org,
        chuck.lever@...cle.com
Cc:     linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] NFS: Fix an off by one in root_nfs_cat()

The intent is to check if the '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>
---
 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;
 }
-- 
2.32.0