linux-kernel - [PATCH] init/version.c: Replace strlcpy with strscpy

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Message-ID: <20230830160806.3821893-1-azeemshaikh38@gmail.com>
Date:   Wed, 30 Aug 2023 16:08:06 +0000
From:   Azeem Shaikh <azeemshaikh38@...il.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-hardening@...r.kernel.org,
        Azeem Shaikh <azeemshaikh38@...il.com>,
        linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] init/version.c: 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 return value of -errno
is used to check for truncation instead of sizeof(dest).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
---
 init/version.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/init/version.c b/init/version.c
index f117921811b4..94c96f6fbfe6 100644
--- a/init/version.c
+++ b/init/version.c
@@ -21,10 +21,10 @@ static int __init early_hostname(char *arg)
 {
 	size_t bufsize = sizeof(init_uts_ns.name.nodename);
 	size_t maxlen  = bufsize - 1;
-	size_t arglen;
+	ssize_t arglen;

-	arglen = strlcpy(init_uts_ns.name.nodename, arg, bufsize);
-	if (arglen > maxlen) {
+	arglen = strscpy(init_uts_ns.name.nodename, arg, bufsize);
+	if (arglen < 0) {
 		pr_warn("hostname parameter exceeds %zd characters and will be truncated",
 			maxlen);
 	}
--
2.41.0.255.g8b1d071c50-goog