commit 820b1984ad61e28fbbdc7194f862c6e2d8edbf8d Author: Nick Mathewson nickm@torproject.org Date: Tue May 3 11:07:49 2016 -0400
Mark three lines unreachable, with extensive docs and use of BUG macros --- src/common/crypto_pwbox.c | 28 ++++++++++++++++++++++------ src/common/crypto_s2k.c | 2 +- 2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/src/common/crypto_pwbox.c b/src/common/crypto_pwbox.c index 819dc0c..31e37c0 100644 --- a/src/common/crypto_pwbox.c +++ b/src/common/crypto_pwbox.c @@ -61,7 +61,7 @@ crypto_pwbox(uint8_t **out, size_t *outlen_out, pwbox_encoded_getarray_skey_header(enc), S2K_MAXLEN, s2k_flags); - if (spec_len < 0 || spec_len > S2K_MAXLEN) + if (BUG(spec_len < 0 || spec_len > S2K_MAXLEN)) goto err; pwbox_encoded_setlen_skey_header(enc, spec_len); enc->header_len = spec_len; @@ -76,10 +76,11 @@ crypto_pwbox(uint8_t **out, size_t *outlen_out,
/* Now that all the data is in position, derive some keys, encrypt, and * digest */ - if (secret_to_key_derivekey(keys, sizeof(keys), + const int s2k_rv = secret_to_key_derivekey(keys, sizeof(keys), pwbox_encoded_getarray_skey_header(enc), spec_len, - secret, secret_len) < 0) + secret, secret_len); + if (BUG(s2k_rv < 0)) goto err;
cipher = crypto_cipher_new_with_iv((char*)keys, (char*)enc->iv); @@ -87,11 +88,11 @@ crypto_pwbox(uint8_t **out, size_t *outlen_out, crypto_cipher_free(cipher);
result_len = pwbox_encoded_encoded_len(enc); - if (result_len < 0) + if (BUG(result_len < 0)) goto err; result = tor_malloc(result_len); enc_len = pwbox_encoded_encode(result, result_len, enc); - if (enc_len < 0) + if (BUG(enc_len < 0)) goto err; tor_assert(enc_len == result_len);
@@ -107,9 +108,24 @@ crypto_pwbox(uint8_t **out, size_t *outlen_out, goto out;
err: + /* LCOV_EXCL_START + + This error case is often unreachable if we're correctly coded, unless + somebody adds a new error case somewhere, or unless you're building + without scrypto support. + + - make_specifier can't fail, unless S2K_MAX_LEN is too short. + - secret_to_key_derivekey can't really fail unless we're missing + scrypt, or the underlying function fails, or we pass it a bogus + algorithm or parameters. + - pwbox_encoded_encoded_len can't fail unless we're using trunnel + incorrectly. + - pwbox_encoded_encode can't fail unless we're using trunnel wrong, + or it's buggy. + */ tor_free(result); rv = -1; - + /* LCOV_EXCL_STOP */ out: pwbox_encoded_free(enc); memwipe(keys, 0, sizeof(keys)); diff --git a/src/common/crypto_s2k.c b/src/common/crypto_s2k.c index 149c393..850a963 100644 --- a/src/common/crypto_s2k.c +++ b/src/common/crypto_s2k.c @@ -170,7 +170,7 @@ make_specifier(uint8_t *spec_out, uint8_t type, unsigned flags) spec_out[SCRYPT_SPEC_LEN-1] = (3u << 4) | (1u << 0); break; default: - tor_fragile_assert(); + tor_fragile_assert(); // LCOV_EXCL_LINE - we should have returned above. return S2K_BAD_ALGORITHM; }