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@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>

diff --git a/init/version.c b/init/version.c
index f117921811b45a1138acc9aafc1d0ee9b3aaaae8..94c96f6fbfe6a277b79c02070620949b5bfa566b 100644 (file)
--- 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);
        }