[PATCH 6.6.y 1/2] init/version.c: Replace strlcpy with strscpy

[Sasha Levin <sashal@kernel.org>]

From: Azeem Shaikh <azeemshaikh38@gmail.com>

[ Upstream commit 8ebab155ea18a6d6c47b17287a0ab4633334f6eb ]

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@gmail.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230830160806.3821893-1-azeemshaikh38@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Stable-dep-of: b6bec5b63a5b ("init: fix early boot crash with bare hostname parameter")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 init/version.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/init/version.c b/init/version.c
index f117921811b45..94c96f6fbfe6a 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);
 	}
-- 
2.53.0