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authorJouni Malinen <j@w1.fi>2015-05-01 13:37:45 (GMT)
committerJouni Malinen <j@w1.fi>2015-05-03 15:26:50 (GMT)
commitdd2f043c9c43d156494e33d7ce22db96e6ef42c7 (patch)
tree6da2c13fbe5ce7ed17db76df4a914ba18cadb74b /src/eap_peer/eap_pwd.c
parentf79a5fa0068d7c770b2631e3030bca07892f99fe (diff)
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EAP-pwd peer: Fix payload length validation for Commit and Confirm
The length of the received Commit and Confirm message payloads was not checked before reading them. This could result in a buffer read overflow when processing an invalid message. Fix this by verifying that the payload is of expected length before processing it. In addition, enforce correct state transition sequence to make sure there is no unexpected behavior if receiving a Commit/Confirm message before the previous exchanges have been completed. Thanks to Kostya Kortchinsky of Google security team for discovering and reporting this issue. Signed-off-by: Jouni Malinen <j@w1.fi>
Diffstat (limited to 'src/eap_peer/eap_pwd.c')
-rw-r--r--src/eap_peer/eap_pwd.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/src/eap_peer/eap_pwd.c b/src/eap_peer/eap_pwd.c
index f2b0926..a629437 100644
--- a/src/eap_peer/eap_pwd.c
+++ b/src/eap_peer/eap_pwd.c
@@ -355,6 +355,23 @@ eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL;
u16 offset;
u8 *ptr, *scalar = NULL, *element = NULL;
+ size_t prime_len, order_len;
+
+ if (data->state != PWD_Commit_Req) {
+ ret->ignore = TRUE;
+ goto fin;
+ }
+
+ prime_len = BN_num_bytes(data->grp->prime);
+ order_len = BN_num_bytes(data->grp->order);
+
+ if (payload_len != 2 * prime_len + order_len) {
+ wpa_printf(MSG_INFO,
+ "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
+ (unsigned int) payload_len,
+ (unsigned int) (2 * prime_len + order_len));
+ goto fin;
+ }
if (((data->private_value = BN_new()) == NULL) ||
((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
@@ -554,6 +571,18 @@ eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
int offset;
+ if (data->state != PWD_Confirm_Req) {
+ ret->ignore = TRUE;
+ goto fin;
+ }
+
+ if (payload_len != SHA256_MAC_LEN) {
+ wpa_printf(MSG_INFO,
+ "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
+ (unsigned int) payload_len, SHA256_MAC_LEN);
+ goto fin;
+ }
+
/*
* first build up the ciphersuite which is group | random_function |
* prf