diff options
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 3a293f919af9..4c9adb4f3d5d 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -318,6 +318,13 @@ static void crng_reseed(bool force) * the resultant ChaCha state to the user, along with the second * half of the block containing 32 bytes of random data that may * be used; random_data_len may not be greater than 32. + * + * The returned ChaCha state contains within it a copy of the old + * key value, at index 4, so the state should always be zeroed out + * immediately after using in order to maintain forward secrecy. + * If the state cannot be erased in a timely manner, then it is + * safer to set the random_data parameter to &chacha_state[4] so + * that this function overwrites it before returning. */ static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], u32 chacha_state[CHACHA_STATE_WORDS], @@ -333,7 +340,7 @@ static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], chacha20_block(chacha_state, first_block); memcpy(key, first_block, CHACHA_KEY_SIZE); - memmove(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); + memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len); memzero_explicit(first_block, sizeof(first_block)); } |