From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx> [ Upstream commit e8c99200b4d117c340c392ebd5e62d85dfeed027 ] In set_secret(), key->tfm is assigned to NULL on line 55, and then ceph_crypto_key_destroy(key) is executed. ceph_crypto_key_destroy(key) crypto_free_sync_skcipher(key->tfm) crypto_free_skcipher(&tfm->base); This happens to work because crypto_sync_skcipher is a trivial wrapper around crypto_skcipher: &tfm->base is still 0 and crypto_free_skcipher() handles that. Let's not rely on the layout of crypto_sync_skcipher. This bug is found by a static analysis tool STCheck written by us. Fixes: 69d6302b65a8 ("libceph: Remove VLA usage of skcipher"). Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx> Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/ceph/crypto.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ceph/crypto.c b/net/ceph/crypto.c index 5d6724cee38f9..4f75df40fb121 100644 --- a/net/ceph/crypto.c +++ b/net/ceph/crypto.c @@ -136,8 +136,10 @@ void ceph_crypto_key_destroy(struct ceph_crypto_key *key) if (key) { kfree(key->key); key->key = NULL; - crypto_free_sync_skcipher(key->tfm); - key->tfm = NULL; + if (key->tfm) { + crypto_free_sync_skcipher(key->tfm); + key->tfm = NULL; + } } } -- 2.20.1