On Mon, Apr 29, 2024 at 08:50:30PM +0000, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> This kernel config option is simply assigned with the resume_file
> buffer. It should be NUL-terminated but not necessarily NUL-padded as
> per its further usage with other string apis:
> | static int __init find_resume_device(void)
> | {
> | if (!strlen(resume_file))
> | return -ENOENT;
> |
> | pm_pr_dbg("Checking hibernation image partition %s\n",
> resume_file);
>
> Use strscpy [2] as it guarantees NUL-termination on the destination
> buffer. Specifically, use the new 2-argument version of strscpy()
> introduced in Commit e6584c3964f2f ("string: Allow 2-argument
> strscpy()").
>
> Link:
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested only.
>
> Found with: $ rg "strncpy\("
> ---
> kernel/power/hibernate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 43b1a82e800c..0a213f69a9e4 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -1361,7 +1361,7 @@ static int __init resume_setup(char *str)
> if (noresume)
> return 1;
>
> - strncpy(resume_file, str, 255);
> + strscpy(resume_file, str);
> return 1;
> }
>
Yup, this looks correct to me. resume_file is:
static char resume_file[256] = CONFIG_PM_STD_PARTITION;
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
