commit f3916a685594a6e0e4f4a215a57f5aea34c8570c Author: Robert Ransom <rransom.8774@gmail.com> Date: Sat Sep 15 02:47:14 2012 -0700 Make crypto_pk_cmp_keys do something sane for NULL keys Fixes bug 4283; bugfix on r76 (Git commit 01aadefbfc7dbd99ddaff922b897996b768cf2f9). --- src/common/crypto.c | 18 +++++++++++------- 1 files changed, 11 insertions(+), 7 deletions(-) diff --git a/src/common/crypto.c b/src/common/crypto.c index 7768cc3..5b5fb75 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -748,19 +748,23 @@ crypto_pk_public_exponent_ok(crypto_pk_t *env) return BN_is_word(env->key->e, 65537); } -/** Compare the public-key components of a and b. Return -1 if a\<b, 0 - * if a==b, and 1 if a\>b. +/** Compare the public-key components of a and b. Return -1 if a\<b, + * 0 if a==b, and 1 if a\>b. A NULL key is considered to be less than + * all non-NULL keys, and equal to itself. + * + * Note that this may leak information about the keys through timing. */ int crypto_pk_cmp_keys(crypto_pk_t *a, crypto_pk_t *b) { int result; + char a_is_non_null = (a != NULL) && (a->key != NULL); + char b_is_non_null = (b != NULL) && (b->key != NULL); + char an_argument_is_null = !a_is_non_null | !b_is_non_null; - if (!a || !b) - return -1; - - if (!a->key || !b->key) - return -1; + result = tor_memcmp(&a_is_non_null, &b_is_non_null, sizeof(a_is_non_null)); + if (an_argument_is_null) + return result; tor_assert(PUBLIC_KEY_OK(a)); tor_assert(PUBLIC_KEY_OK(b));