67 lines
2.3 KiB
Diff
67 lines
2.3 KiB
Diff
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From e28a58be26184c2a23f80b410e0997ef1bd5d578 Mon Sep 17 00:00:00 2001
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From: Jouni Malinen <j@w1.fi>
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Date: Fri, 1 May 2015 16:40:44 +0300
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Subject: [PATCH 2/5] EAP-pwd server: Fix payload length validation for Commit
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and Confirm
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The length of the received Commit and Confirm message payloads was not
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checked before reading them. This could result in a buffer read
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overflow when processing an invalid message.
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Fix this by verifying that the payload is of expected length before
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processing it. In addition, enforce correct state transition sequence to
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make sure there is no unexpected behavior if receiving a Commit/Confirm
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message before the previous exchanges have been completed.
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Thanks to Kostya Kortchinsky of Google security team for discovering and
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reporting this issue.
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Signed-off-by: Jouni Malinen <j@w1.fi>
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---
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src/eap_server/eap_server_pwd.c | 19 +++++++++++++++++++
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1 file changed, 19 insertions(+)
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diff --git a/src/eap_server/eap_server_pwd.c b/src/eap_server/eap_server_pwd.c
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index 66bd5d2..3189105 100644
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--- a/src/eap_server/eap_server_pwd.c
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+++ b/src/eap_server/eap_server_pwd.c
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@@ -656,9 +656,21 @@ eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
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BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
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EC_POINT *K = NULL, *point = NULL;
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int res = 0;
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+ size_t prime_len, order_len;
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wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
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+ prime_len = BN_num_bytes(data->grp->prime);
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+ order_len = BN_num_bytes(data->grp->order);
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+
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+ if (payload_len != 2 * prime_len + order_len) {
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+ wpa_printf(MSG_INFO,
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+ "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
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+ (unsigned int) payload_len,
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+ (unsigned int) (2 * prime_len + order_len));
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+ goto fin;
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+ }
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+
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if (((data->peer_scalar = BN_new()) == NULL) ||
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((data->k = BN_new()) == NULL) ||
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((cofactor = BN_new()) == NULL) ||
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@@ -774,6 +786,13 @@ eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
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u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
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int offset;
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+ if (payload_len != SHA256_MAC_LEN) {
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+ wpa_printf(MSG_INFO,
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+ "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
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+ (unsigned int) payload_len, SHA256_MAC_LEN);
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+ goto fin;
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+ }
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+
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/* build up the ciphersuite: group | random_function | prf */
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grp = htons(data->group_num);
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ptr = (u8 *) &cs;
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--
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1.9.1
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