commit ab6ad3c040de68b1f06b8f910407bff570b24b43 Author: Nick Mathewson nickm@torproject.org Date: Wed Mar 6 09:59:10 2019 -0500

Drop thread-local fast_rng on fork.

This will cause the child process to construct a new one in a nice safe way.

Closes ticket 29668; bug not in any released Tor. --- src/lib/crypt_ops/crypto_init.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/src/lib/crypt_ops/crypto_init.c b/src/lib/crypt_ops/crypto_init.c index cf491f32d..5c2780b2c 100644 --- a/src/lib/crypt_ops/crypto_init.c +++ b/src/lib/crypt_ops/crypto_init.c @@ -152,6 +152,12 @@ crypto_prefork(void) #ifdef ENABLE_NSS crypto_nss_prefork(); #endif + /* It is not safe to share a fast_rng object across a fork boundary unless + * we actually have zero-on-fork support in map_anon.c. If we have + * drop-on-fork support, we will crash; if we have neither, we will yield + * a copy of the parent process's rng, which is scary and insecure. + */ + destroy_thread_fast_rng(); }

/** Run operations that the crypto library requires to be happy again