linux-kernel - [PATCH 1/2] dm-crypt: Use up_read() together with key_put() only once in crypt_set_keyring

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Message-ID: <ab7f53e6-128b-4c75-8227-b38a10d134b6@web.de>
Date: Wed, 18 Sep 2024 16:08:09 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: dm-devel@...ts.linux.dev, kernel-janitors@...r.kernel.org,
 Alasdair Kergon <agk@...hat.com>, Mike Snitzer <snitzer@...nel.org>,
 Mikulas Patocka <mpatocka@...hat.com>, Ondrej Kozina <okozina@...hat.com>,
 Waiman Long <longman@...hat.com>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] dm-crypt: Use up_read() together with key_put() only once
 in crypt_set_keyring_key()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Wed, 18 Sep 2024 15:05:29 +0200

The combination of the calls “up_read(&key->sem)” and “key_put(key)”
was immediately used after a return code check for a set_key() call
in this function implementation.
Thus use such a function call pair only once instead directly
before the check.

This issue was transformed by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 drivers/md/dm-crypt.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index d5533b43054e..dae2fe3cb182 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2621,16 +2621,13 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
 	down_read(&key->sem);

 	ret = set_key(cc, key);
+	up_read(&key->sem);
+	key_put(key);
 	if (ret < 0) {
-		up_read(&key->sem);
-		key_put(key);
 		kfree_sensitive(new_key_string);
 		return ret;
 	}

-	up_read(&key->sem);
-	key_put(key);
-
 	/* clear the flag since following operations may invalidate previously valid key */
 	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);

--
2.46.0