* [PATCH] dax: refactor deprecated strncpy
@ 2023-09-13 1:10 Justin Stitt
2023-09-13 15:35 ` Dave Jiang
2023-09-15 3:40 ` Kees Cook
0 siblings, 2 replies; 3+ messages in thread
From: Justin Stitt @ 2023-09-13 1:10 UTC (permalink / raw)
To: Dan Williams, Vishal Verma, Dave Jiang
Cc: nvdimm, linux-cxl, linux-kernel, linux-hardening, Justin Stitt
`strncpy` is deprecated for use on NUL-terminated destination strings [1].
We should prefer more robust and less ambiguous string interfaces.
`dax_id->dev_name` is expected to be NUL-terminated and has been zero-allocated.
A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer. Moreover, due to
`dax_id` being zero-allocated the padding behavior of `strncpy` is not
needed and a simple 1:1 replacement of strncpy -> strscpy should
suffice.
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: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.
---
drivers/dax/bus.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 0ee96e6fc426..1659b787b65f 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -103,7 +103,7 @@ static ssize_t do_id_store(struct device_driver *drv, const char *buf,
if (action == ID_ADD) {
dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
if (dax_id) {
- strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
+ strscpy(dax_id->dev_name, buf, DAX_NAME_LEN);
list_add(&dax_id->list, &dax_drv->ids);
} else
rc = -ENOMEM;
---
base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230913-strncpy-drivers-dax-bus-c-f12e3153e44b
Best regards,
--
Justin Stitt <justinstitt@google.com>
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] dax: refactor deprecated strncpy
2023-09-13 1:10 [PATCH] dax: refactor deprecated strncpy Justin Stitt
@ 2023-09-13 15:35 ` Dave Jiang
2023-09-15 3:40 ` Kees Cook
1 sibling, 0 replies; 3+ messages in thread
From: Dave Jiang @ 2023-09-13 15:35 UTC (permalink / raw)
To: Justin Stitt, Dan Williams, Vishal Verma
Cc: nvdimm, linux-cxl, linux-kernel, linux-hardening
On 9/12/23 18:10, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> `dax_id->dev_name` is expected to be NUL-terminated and has been zero-allocated.
>
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer. Moreover, due to
> `dax_id` being zero-allocated the padding behavior of `strncpy` is not
> needed and a simple 1:1 replacement of strncpy -> strscpy should
> suffice.
>
> 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: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
> Note: build-tested only.
> ---
> drivers/dax/bus.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 0ee96e6fc426..1659b787b65f 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -103,7 +103,7 @@ static ssize_t do_id_store(struct device_driver *drv, const char *buf,
> if (action == ID_ADD) {
> dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
> if (dax_id) {
> - strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
> + strscpy(dax_id->dev_name, buf, DAX_NAME_LEN);
> list_add(&dax_id->list, &dax_drv->ids);
> } else
> rc = -ENOMEM;
>
> ---
> base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
> change-id: 20230913-strncpy-drivers-dax-bus-c-f12e3153e44b
>
> Best regards,
> --
> Justin Stitt <justinstitt@google.com>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] dax: refactor deprecated strncpy
2023-09-13 1:10 [PATCH] dax: refactor deprecated strncpy Justin Stitt
2023-09-13 15:35 ` Dave Jiang
@ 2023-09-15 3:40 ` Kees Cook
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2023-09-15 3:40 UTC (permalink / raw)
To: Justin Stitt
Cc: Dan Williams, Vishal Verma, Dave Jiang, nvdimm, linux-cxl,
linux-kernel, linux-hardening
On Wed, Sep 13, 2023 at 01:10:24AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> `dax_id->dev_name` is expected to be NUL-terminated and has been zero-allocated.
>
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer. Moreover, due to
> `dax_id` being zero-allocated the padding behavior of `strncpy` is not
> needed and a simple 1:1 replacement of strncpy -> strscpy should
> suffice.
>
> 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: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
Looks correct to me.
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-09-13 1:10 [PATCH] dax: refactor deprecated strncpy Justin Stitt
2023-09-13 15:35 ` Dave Jiang
2023-09-15 3:40 ` Kees Cook
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