From: Kees Cook <keescook@chromium.org>
To: laniel_francis@privacyrequired.com
Cc: linux-hardening@vger.kernel.org
Subject: Re: [PATCH v1 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy.
Date: Fri, 16 Oct 2020 16:19:59 -0700 [thread overview]
Message-ID: <202010161618.8E214473@keescook> (raw)
In-Reply-To: <20201016125216.10922-2-laniel_francis@privacyrequired.com>
On Fri, Oct 16, 2020 at 02:52:14PM +0200, laniel_francis@privacyrequired.com wrote:
> From: Francis Laniel <laniel_francis@privacyrequired.com>
>
> This patch solves part 1 of issue: https://github.com/KSPP/linux/issues/110
>
> Signed-off-by: Francis Laniel <laniel_francis@privacyrequired.com>
> ---
> lib/nlattr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/nlattr.c b/lib/nlattr.c
> index 74019c8ebf6b..ab96a5f4b9b8 100644
> --- a/lib/nlattr.c
> +++ b/lib/nlattr.c
> @@ -731,8 +731,8 @@ size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
> if (dstsize > 0) {
> size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
>
> - memset(dst, 0, dstsize);
> memcpy(dst, src, len);
> + dst[len] = '\0';
I don't think this is right: callers are likely depending on the entire
destination buffer to be zero-padded. I think you probably want:
memset(dst + len, 0, dstsize - len);
memcpy(dst, src, len);
(but double-check my pointer math)
> }
>
> return srclen;
> --
> 2.20.1
>
--
Kees Cook
next prev parent reply other threads:[~2020-10-16 23:20 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-16 12:52 [RFC][PATCH v1] Fix and rename nla_strlcpy to nla_strcpy laniel_francis
2020-10-16 12:52 ` [PATCH v1 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy laniel_francis
2020-10-16 23:19 ` Kees Cook [this message]
2020-10-17 8:50 ` Francis Laniel
2020-10-16 23:29 ` Jann Horn
2020-10-17 8:50 ` Francis Laniel
2020-10-16 12:52 ` [PATCH v1 2/3] Modify return value of nla_strlcpy to match that of strscpy laniel_francis
2020-10-16 23:23 ` Kees Cook
2020-10-17 8:53 ` Francis Laniel
2020-10-17 0:41 ` Jann Horn
2020-10-17 8:56 ` Francis Laniel
2020-10-16 12:52 ` [PATCH v1 3/3] Rename nla_strlcpy to nla_strcpy laniel_francis
2020-10-16 23:18 ` Kees Cook
2020-10-19 15:23 ` [RFC][PATCH v2 0/3] Fix inefficiences and rename nla_strlcpy laniel_francis
2020-10-19 15:23 ` [RFC][PATCH v2 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy laniel_francis
2020-10-19 15:23 ` [RFC][PATCH v2 2/3] Modify return value of nla_strlcpy to match that of strscpy laniel_francis
2020-10-19 16:43 ` Jakub Kicinski
2020-10-19 23:01 ` Kees Cook
2020-10-19 23:34 ` Jakub Kicinski
2020-10-20 10:28 ` Francis Laniel
2020-10-20 17:23 ` Kees Cook
2020-10-20 17:19 ` Kees Cook
2020-10-20 13:05 ` Francis Laniel
2020-10-20 10:17 ` Francis Laniel
2020-10-19 15:23 ` [RFC][PATCH v2 3/3] Rename nla_strlcpy to nla_strcpy laniel_francis
2020-10-19 16:45 ` [RFC][PATCH v2 0/3] Fix inefficiences and rename nla_strlcpy Jakub Kicinski
2020-10-19 22:58 ` Kees Cook
2020-10-19 23:34 ` Jakub Kicinski
2020-10-20 10:18 ` Francis Laniel
2020-10-19 23:03 ` Kees Cook
2020-10-20 13:06 ` Francis Laniel
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