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EAP-pwd server: 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-2015-5314)

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-11-01 18:24:16 +02:00
parent 8057821706
commit bef802ece0
1 changed files with 3 additions and 3 deletions
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6
src/eap_server/eap_server_pwd.c
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@ -970,7 +970,7 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv,
/*
* the first and all intermediate fragments have the M bit set
*/
if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
"attack detected! (%d+%d > %d)",
@ -981,6 +981,8 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv,
}
wpabuf_put_data(data->inbuf, pos, len);
data->in_frag_pos += len;
}
if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
(int) len);
return;
@ -990,8 +992,6 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv,
* buffering fragments so that's how we know it's the last)
*/
if (data->in_frag_pos) {
wpabuf_put_data(data->inbuf, pos, len);
data->in_frag_pos += len;
pos = wpabuf_head_u8(data->inbuf);
len = data->in_frag_pos;
wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",