From cb69f36ba1f8d5e73c46538e84a88178fb17f23d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 13 Aug 2013 15:02:27 -0700 Subject: ecryptfs: avoid ctx initialization race It might be possible for two callers to race the mutex lock after the NULL ctx check. Instead, move the lock above the check so there isn't the possibility of leaking a crypto ctx. Additionally, report the full algo name when failing. Signed-off-by: Kees Cook [tyhicks: remove out label, which is no longer used] Signed-off-by: Tyler Hicks --- fs/ecryptfs/crypto.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'fs/ecryptfs') diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c index 3bd35e24b9e9..c88e355f7635 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -614,30 +614,30 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat) "key_size_bits = [%zd]\n", crypt_stat->cipher, (int)strlen(crypt_stat->cipher), crypt_stat->key_size << 3); + mutex_lock(&crypt_stat->cs_tfm_mutex); if (crypt_stat->tfm) { rc = 0; - goto out; + goto out_unlock; } - mutex_lock(&crypt_stat->cs_tfm_mutex); rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, crypt_stat->cipher, "cbc"); if (rc) goto out_unlock; crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0); - kfree(full_alg_name); if (IS_ERR(crypt_stat->tfm)) { rc = PTR_ERR(crypt_stat->tfm); crypt_stat->tfm = NULL; ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): " "Error initializing cipher [%s]\n", - crypt_stat->cipher); - goto out_unlock; + full_alg_name); + goto out_free; } crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY); rc = 0; +out_free: + kfree(full_alg_name); out_unlock: mutex_unlock(&crypt_stat->cs_tfm_mutex); -out: return rc; } -- cgit v1.2.3