linux-kernel - [PATCH] aoe: refactor deprecated strncpy

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Message-ID: <20230911-strncpy-drivers-block-aoe-aoenet-c-v1-1-9643d6137ff9@google.com>
Date:   Mon, 11 Sep 2023 21:09:07 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Justin Sanders <justin@...aid.com>, Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Xu Panda <xu.panda@....com.cn>,
        Yang Yang <yang.yang29@....com>,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] aoe: refactor deprecated strncpy

`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: linux-hardening@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>
Cc: Xu Panda <xu.panda@....com.cn>
Cc: Yang Yang <yang.yang29@....com>
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: This exact same patch exists [3] but seemed to die so I'm
resending. If it was actually picked-up somewhere then we can ignore
this patch.

[3]: https://lore.kernel.org/all/202212051930256039214@zte.com.cn/
---
 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: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230911-strncpy-drivers-block-aoe-aoenet-c-024debad6105

Best regards,
--
Justin Stitt <justinstitt@...gle.com>