On 2013-08-13 15:02:27, Kees Cook wrote:
> 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 <keescook@xxxxxxxxxxxx>
Thanks, Kees!
I've pushed this to my next branch and it'll be included in a pull
request early next week.
I made one small change to this patch. See below.
> ---
> fs/ecryptfs/crypto.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
> index d107576..c134346 100644
> --- a/fs/ecryptfs/crypto.c
> +++ b/fs/ecryptfs/crypto.c
> @@ -618,27 +618,28 @@ 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:
The out label is no longer used. I removed it when I committed this
patch.
Tyler
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