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Make crypto_pk_cmp_keys do something sane for NULL keys

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Fixes bug 4283; bugfix on r76
(Git commit 01aadefbfc).
This commit is contained in:
Robert Ransom 2012-09-15 02:47:14 -07:00 committed by Nick Mathewson
parent 32d9cea289
commit f3916a6855
1 changed files with 11 additions and 7 deletions
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18
src/common/crypto.c
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@ -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));