linux-kernel - [PATCH 3.16 051/370] dm crypt: mark key as invalid until properly loaded

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Message-ID: <lsq.1489146382.18957275@decadent.org.uk>
Date:   Fri, 10 Mar 2017 11:46:22 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Mikulas Patocka" <mpatocka@...hat.com>,
        "Ondrej Kozina" <okozina@...hat.com>,
        "Mike Snitzer" <snitzer@...hat.com>
Subject: [PATCH 3.16 051/370] dm crypt: mark key as invalid until properly
 loaded

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ondrej Kozina <okozina@...hat.com>

commit 265e9098bac02bc5e36cda21fdbad34cb5b2f48d upstream.

In crypt_set_key(), if a failure occurs while replacing the old key
(e.g. tfm->setkey() fails) the key must not have DM_CRYPT_KEY_VALID flag
set.  Otherwise, the crypto layer would have an invalid key that still
has DM_CRYPT_KEY_VALID flag set.

Signed-off-by: Ondrej Kozina <okozina@...hat.com>
Reviewed-by: Mikulas Patocka <mpatocka@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/md/dm-crypt.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1449,12 +1449,15 @@ static int crypt_set_key(struct crypt_co
 	if (!cc->key_size && strcmp(key, "-"))
 		goto out;
 
+	/* clear the flag since following operations may invalidate previously valid key */
+	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
+
 	if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
 		goto out;
 
-	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
-
 	r = crypt_setkey_allcpus(cc);
+	if (!r)
+		set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
 
 out:
 	/* Hex key string not needed after here, so wipe it. */