strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
data_page wants to be NUL-terminated and NUL-padded, use strscpy_pad to
provide both of these. data_page no longer awkwardly relies on
init_mount to perform its NUL-termination, although that sanity check is
left unchanged.
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\("
---
init/do_mounts.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 3c5fd993bc7e..6af29da8889e 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -159,8 +159,7 @@ static int __init do_mount_root(const char *name, const char *fs,
if (!p)
return -ENOMEM;
data_page = page_address(p);
- /* zero-pad. init_mount() will make sure it's terminated */
- strncpy(data_page, data, PAGE_SIZE);
+ strscpy_pad(data_page, data, PAGE_SIZE);
}
ret = init_mount(name, "/root", fs, flags, data_page);
---
base-commit: 026e680b0a08a62b1d948e5a8ca78700bfac0e6e
change-id: 20240402-strncpy-init-do_mounts-c-e1d378c88049
Best regards,
--
Justin Stitt <[email protected]>
On Tue, Apr 02, 2024 at 08:39:49PM +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.
>
> data_page wants to be NUL-terminated and NUL-padded, use strscpy_pad to
> provide both of these. data_page no longer awkwardly relies on
> init_mount to perform its NUL-termination, although that sanity check is
> left unchanged.
>
> 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]>
This looks good. Thanks!
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On Tue, 02 Apr 2024 20:39:49 +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.
>
> data_page wants to be NUL-terminated and NUL-padded, use strscpy_pad to
> provide both of these. data_page no longer awkwardly relies on
> init_mount to perform its NUL-termination, although that sanity check is
> left unchanged.
>
> [...]
Applied to for-next/hardening, thanks!
[1/1] init: replace deprecated strncpy with strscpy_pad
https://git.kernel.org/kees/c/fa6475acde9a
Take care,
--
Kees Cook