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EAP-FAST server: Avoid undefined behavior in pointer arithmetic

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Reorder terms in a way that no invalid pointers are generated with
pos+len operations. end-pos is always defined (with a valid pos pointer)
while pos+len could end up pointing beyond the end pointer which would
be undefined behavior.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-10-18 11:12:34 +03:00
parent b6f961ab25
commit ed5e3a5888
1 changed files with 19 additions and 14 deletions
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33
src/eap_server/eap_server_fast.c
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@ -180,42 +180,47 @@ static int eap_fast_session_ticket_cb(void *ctx, const u8 *ticket, size_t len,
buf, end - buf);
pos = buf;
while (pos + 1 < end) {
if (pos + 2 + pos[1] > end)
while (end - pos > 1) {
u8 id, elen;
id = *pos++;
elen = *pos++;
if (elen > end - pos)
break;
switch (*pos) {
switch (id) {
case PAC_OPAQUE_TYPE_PAD:
goto done;
case PAC_OPAQUE_TYPE_KEY:
if (pos[1] != EAP_FAST_PAC_KEY_LEN) {
wpa_printf(MSG_DEBUG, "EAP-FAST: Invalid "
"PAC-Key length %d", pos[1]);
if (elen != EAP_FAST_PAC_KEY_LEN) {
wpa_printf(MSG_DEBUG,
"EAP-FAST: Invalid PAC-Key length %d",
elen);
os_free(buf);
return -1;
}
pac_key = pos + 2;
pac_key = pos;
wpa_hexdump_key(MSG_DEBUG, "EAP-FAST: PAC-Key from "
"decrypted PAC-Opaque",
pac_key, EAP_FAST_PAC_KEY_LEN);
break;
case PAC_OPAQUE_TYPE_LIFETIME:
if (pos[1] != 4) {
if (elen != 4) {
wpa_printf(MSG_DEBUG, "EAP-FAST: Invalid "
"PAC-Key lifetime length %d",
pos[1]);
elen);
os_free(buf);
return -1;
}
lifetime = WPA_GET_BE32(pos + 2);
lifetime = WPA_GET_BE32(pos);
break;
case PAC_OPAQUE_TYPE_IDENTITY:
identity = pos + 2;
identity_len = pos[1];
identity = pos;
identity_len = elen;
break;
}
pos += 2 + pos[1];
pos += elen;
}
done:
@ -1134,7 +1139,7 @@ static int eap_fast_parse_tlvs(struct wpabuf *data,
pos = wpabuf_mhead(data);
end = pos + wpabuf_len(data);
while (pos + 4 < end) {
while (end - pos > 4) {
mandatory = pos[0] & 0x80;
tlv_type = WPA_GET_BE16(pos) & 0x3fff;
pos += 2;