From: Justin Stitt <justinstitt@google.com>
Date: Mon, 25 Sep 2023 06:35:54 +0000 (+0000)
Subject: dm crypt: replace open-coded kmemdup_nul
X-Git-Tag: 6.7-rc-smb3-client-fixes-part2~85^2~11
X-Git-Url: http://git.samba.org/?a=commitdiff_plain;h=e9d7bd2c8664aa43866c7985d9050a052516c07d;p=sfrench%2Fcifs-2.6.git

dm crypt: replace open-coded kmemdup_nul

kzalloc() followed by strncpy() on an expected NUL-terminated string is
just kmemdup_nul(). Let's simplify this code (while also dropping a
deprecated strncpy() call [1]).

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index f2662c21a6df..8a03b3590733 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2858,10 +2858,9 @@ static int crypt_ctr_auth_cipher(struct crypt_config *cc, char *cipher_api)
 	if (!start || !end || ++start > end)
 		return -EINVAL;
 
-	mac_alg = kzalloc(end - start + 1, GFP_KERNEL);
+	mac_alg = kmemdup_nul(start, end - start, GFP_KERNEL);
 	if (!mac_alg)
 		return -ENOMEM;
-	strncpy(mac_alg, start, end - start);
 
 	mac = crypto_alloc_ahash(mac_alg, 0, CRYPTO_ALG_ALLOCATES_MEMORY);
 	kfree(mac_alg);