`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
`lc` is already zero-allocated:
| lc = kzalloc(sizeof(*lc), GFP_KERNEL);
... as such, any future NUL-padding is superfluous.
A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.
Let's also go with the more idiomatic `dest, src, sizeof(dest)` pattern
for destination buffers that the compiler can calculate the size for.
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]
Cc: Kees Cook <[email protected]>
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested only.
---
drivers/md/dm-log-userspace-base.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
index 5aace6ee6d47..7e4f27e86150 100644
--- a/drivers/md/dm-log-userspace-base.c
+++ b/drivers/md/dm-log-userspace-base.c
@@ -224,7 +224,7 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
lc->usr_argc = argc;
- strncpy(lc->uuid, argv[0], DM_UUID_LEN);
+ strscpy(lc->uuid, argv[0], sizeof(lc->uuid));
argc--;
argv++;
spin_lock_init(&lc->flush_lock);
---
base-commit: 6465e260f48790807eef06b583b38ca9789b6072
change-id: 20230925-strncpy-drivers-md-dm-log-userspace-base-c-857579d9834f
Best regards,
--
Justin Stitt <[email protected]>
On Mon, Sep 25, 2023 at 07:06:03AM +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.
>
> `lc` is already zero-allocated:
> | lc = kzalloc(sizeof(*lc), GFP_KERNEL);
> ... as such, any future NUL-padding is superfluous.
>
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
>
> Let's also go with the more idiomatic `dest, src, sizeof(dest)` pattern
> for destination buffers that the compiler can calculate the size for.
>
> 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]
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Justin Stitt <[email protected]>
Looks good to me. Thanks for the sizeof() replacement. :)
Reviewed-by: Kees Cook <[email protected]>
-Kees
> ---
> Note: build-tested only.
> ---
> drivers/md/dm-log-userspace-base.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
> index 5aace6ee6d47..7e4f27e86150 100644
> --- a/drivers/md/dm-log-userspace-base.c
> +++ b/drivers/md/dm-log-userspace-base.c
> @@ -224,7 +224,7 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
>
> lc->usr_argc = argc;
>
> - strncpy(lc->uuid, argv[0], DM_UUID_LEN);
> + strscpy(lc->uuid, argv[0], sizeof(lc->uuid));
> argc--;
> argv++;
> spin_lock_init(&lc->flush_lock);
>
> ---
> base-commit: 6465e260f48790807eef06b583b38ca9789b6072
> change-id: 20230925-strncpy-drivers-md-dm-log-userspace-base-c-857579d9834f
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
--
Kees Cook
On Mon, 25 Sep 2023 07:06:03 +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.
>
> `lc` is already zero-allocated:
> | lc = kzalloc(sizeof(*lc), GFP_KERNEL);
> ... as such, any future NUL-padding is superfluous.
>
> [...]
Applied to for-next/hardening, thanks!
[1/1] dm log userspace: replace deprecated strncpy with strscpy
https://git.kernel.org/kees/c/f8cff5441800
Take care,
--
Kees Cook