2023-09-19 11:19:07

by Justin Stitt

[permalink] [raw]
Subject: [PATCH v2] aoe: replace strncpy with strscpy

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

`aoe_iflist` is expected to be NUL-terminated which is evident by its
use with string apis later on like `strspn`:
| p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);

It also seems `aoe_iflist` does not need to be NUL-padded which means
`strscpy` [2] is a suitable replacement due to the fact that it
guarantees NUL-termination on the destination buffer while not
unnecessarily NUL-padding.

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]>
Cc: Xu Panda <[email protected]>
Cc: Yang Yang <[email protected]>
Signed-off-by: Justin Stitt <[email protected]>
---
Changes in v2:
- reword subject line (thanks Jens)
- rebase onto 3669558bdf35
- Link to v1: https://lore.kernel.org/r/20230911-strncpy-drivers-block-aoe-aoenet-c-v1-1-9643d6137ff9@google.com
---
Note: This exact same patch exists [3] but seemed to die so I'm
resending.

[3]: https://lore.kernel.org/all/[email protected]/
---
drivers/block/aoe/aoenet.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/block/aoe/aoenet.c b/drivers/block/aoe/aoenet.c
index 63773a90581d..c51ea95bc2ce 100644
--- a/drivers/block/aoe/aoenet.c
+++ b/drivers/block/aoe/aoenet.c
@@ -39,8 +39,7 @@ static struct ktstate kts;
#ifndef MODULE
static int __init aoe_iflist_setup(char *str)
{
- strncpy(aoe_iflist, str, IFLISTSZ);
- aoe_iflist[IFLISTSZ - 1] = '\0';
+ strscpy(aoe_iflist, str, IFLISTSZ);
return 1;
}


---
base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec
change-id: 20230911-strncpy-drivers-block-aoe-aoenet-c-024debad6105

Best regards,
--
Justin Stitt <[email protected]>


2023-09-20 20:54:29

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH v2] aoe: replace strncpy with strscpy

On Tue, Sep 19, 2023 at 05:27:45AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> `aoe_iflist` is expected to be NUL-terminated which is evident by its
> use with string apis later on like `strspn`:
> | p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);
>
> It also seems `aoe_iflist` does not need to be NUL-padded which means
> `strscpy` [2] is a suitable replacement due to the fact that it
> guarantees NUL-termination on the destination buffer while not
> unnecessarily NUL-padding.
>
> 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]>
> Cc: Xu Panda <[email protected]>
> Cc: Yang Yang <[email protected]>
> Signed-off-by: Justin Stitt <[email protected]>

Looks right. Thanks!

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook

2023-10-03 23:58:26

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH v2] aoe: replace strncpy with strscpy

On Tue, Sep 19, 2023 at 05:27:45AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> `aoe_iflist` is expected to be NUL-terminated which is evident by its
> use with string apis later on like `strspn`:
> | p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);
>
> It also seems `aoe_iflist` does not need to be NUL-padded which means
> `strscpy` [2] is a suitable replacement due to the fact that it
> guarantees NUL-termination on the destination buffer while not
> unnecessarily NUL-padding.
>
> 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]>
> Cc: Xu Panda <[email protected]>
> Cc: Yang Yang <[email protected]>
> Signed-off-by: Justin Stitt <[email protected]>

Friendly ping on this patch. Jens, do you want to pick this up?

--
Kees Cook

2023-10-04 00:24:06

by Jens Axboe

[permalink] [raw]
Subject: Re: [PATCH v2] aoe: replace strncpy with strscpy


On Tue, 19 Sep 2023 05:27:45 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> `aoe_iflist` is expected to be NUL-terminated which is evident by its
> use with string apis later on like `strspn`:
> | p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);
>
> It also seems `aoe_iflist` does not need to be NUL-padded which means
> `strscpy` [2] is a suitable replacement due to the fact that it
> guarantees NUL-termination on the destination buffer while not
> unnecessarily NUL-padding.
>
> [...]

Applied, thanks!

[1/1] aoe: replace strncpy with strscpy
commit: 5e9b7cfc209b84d135993b8cb75ea383f24b2bba

Best regards,
--
Jens Axboe