[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <202308301415.42CAF1C13B@keescook>
Date: Wed, 30 Aug 2023 14:17:12 -0700
From: Kees Cook <keescook@...omium.org>
To: Azeem Shaikh <azeemshaikh38@...il.com>
Cc: linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
Masahiro Yamada <masahiroy@...nel.org>,
Thomas Weißschuh <linux@...ssschuh.net>
Subject: Re: [PATCH] init/version.c: Replace strlcpy with strscpy
On Wed, Aug 30, 2023 at 04:08:06PM +0000, Azeem Shaikh wrote:
> 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) {
nitpick: this is no longer "length of arg", it's the length of the
destination string. Regardless:
Reviewed-by: Kees Cook <keescook@...omium.org>
> pr_warn("hostname parameter exceeds %zd characters and will be truncated",
> maxlen);
> }
> --
> 2.41.0.255.g8b1d071c50-goog
>
>
--
Kees Cook
Powered by blists - more mailing lists