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EAP-pwd peer: Fix last fragment length validation

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All but the last fragment had their length checked against the remaining
room in the reassembly buffer. This allowed a suitably constructed last
fragment frame to try to add extra data that would go beyond the buffer.
The length validation code in wpabuf_put_data() prevents an actual
buffer write overflow from occurring, but this results in process
termination. (CVE-2015-5315)

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-11-01 18:18:17 +02:00
parent 03ed0a5239
commit 8057821706
1 changed files with 3 additions and 4 deletions
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7
src/eap_peer/eap_pwd.c
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@ -903,7 +903,7 @@ eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
/* /*
* buffer and ACK the fragment * buffer and ACK the fragment
*/ */
if (EAP_PWD_GET_MORE_BIT(lm_exch)) { if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
data->in_frag_pos += len; data->in_frag_pos += len;
if (data->in_frag_pos > wpabuf_size(data->inbuf)) { if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack " wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
@ -916,7 +916,8 @@ eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
return NULL; return NULL;
} }
wpabuf_put_data(data->inbuf, pos, len); wpabuf_put_data(data->inbuf, pos, len);
}
if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
EAP_PWD_HDR_SIZE, EAP_PWD_HDR_SIZE,
EAP_CODE_RESPONSE, eap_get_id(reqData)); EAP_CODE_RESPONSE, eap_get_id(reqData));
@ -930,10 +931,8 @@ eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
* we're buffering and this is the last fragment * we're buffering and this is the last fragment
*/ */
if (data->in_frag_pos) { if (data->in_frag_pos) {
wpabuf_put_data(data->inbuf, pos, len);
wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
(int) len); (int) len);
data->in_frag_pos += len;
pos = wpabuf_head_u8(data->inbuf); pos = wpabuf_head_u8(data->inbuf);
len = data->in_frag_pos; len = data->in_frag_pos;
} }