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pki_crypto.c: plug ecdsa_sig->[r,s] bignum leaks

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Per ecdsa(3ssl), ECDSA_SIG_new does allocate its 'r' and 's' bignum fields.
Fix a bug where the initial 'r' and 's' bignums were being overwritten with
newly-allocated bignums, resulting in a memory leak.

BUG: https://red.libssh.org/issues/175

Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

(cherry picked from commit 4745d652b5)
This commit is contained in:
Jon Simons
2014-10-05 05:59:54 -07:00
committed by Andreas Schneider
parent 32a3cfe661
commit 5d75090d9f
3 changed files with 12 additions and 3 deletions
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2
include/libssh/dh.h
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@@ -49,7 +49,7 @@ int hashbufin_add_cookie(ssh_session session, unsigned char *cookie);
int hashbufout_add_cookie(ssh_session session); int hashbufout_add_cookie(ssh_session session);
int generate_session_keys(ssh_session session); int generate_session_keys(ssh_session session);
bignum make_string_bn(ssh_string string); bignum make_string_bn(ssh_string string);
void make_string_bn_inplace(ssh_string string, bignum bnout);
ssh_string make_bignum_string(bignum num); ssh_string make_bignum_string(bignum num);
#endif /* DH_H_ */ #endif /* DH_H_ */

9
src/dh.c
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@@ -407,6 +407,15 @@ bignum make_string_bn(ssh_string string){
return bn; return bn;
} }
void make_string_bn_inplace(ssh_string string, bignum bnout) {
unsigned int len = ssh_string_len(string);
#ifdef HAVE_LIBGCRYPT
#error "unsupported"
#elif defined HAVE_LIBCRYPTO
bignum_bin2bn(string->data, len, bnout);
#endif
}
ssh_string dh_get_e(ssh_session session) { ssh_string dh_get_e(ssh_session session) {
return make_bignum_string(session->next_crypto->e); return make_bignum_string(session->next_crypto->e);
} }

4
src/pki_crypto.c
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@@ -1397,7 +1397,7 @@ ssh_signature pki_signature_from_blob(const ssh_key pubkey,
ssh_print_hexa("r", ssh_string_data(r), ssh_string_len(r)); ssh_print_hexa("r", ssh_string_data(r), ssh_string_len(r));
#endif #endif
sig->ecdsa_sig->r = make_string_bn(r); make_string_bn_inplace(r, sig->ecdsa_sig->r);
ssh_string_burn(r); ssh_string_burn(r);
ssh_string_free(r); ssh_string_free(r);
if (sig->ecdsa_sig->r == NULL) { if (sig->ecdsa_sig->r == NULL) {
@@ -1418,7 +1418,7 @@ ssh_signature pki_signature_from_blob(const ssh_key pubkey,
ssh_print_hexa("s", ssh_string_data(s), ssh_string_len(s)); ssh_print_hexa("s", ssh_string_data(s), ssh_string_len(s));
#endif #endif
sig->ecdsa_sig->s = make_string_bn(s); make_string_bn_inplace(s, sig->ecdsa_sig->s);
ssh_string_burn(s); ssh_string_burn(s);
ssh_string_free(s); ssh_string_free(s);
if (sig->ecdsa_sig->s == NULL) { if (sig->ecdsa_sig->s == NULL) {