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RSN: 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 17:16:39 +03:00
parent f758ae7665
commit 2461724c05
2 changed files with 5 additions and 5 deletions
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4
src/rsn_supp/wpa.c
View file

@ -1003,8 +1003,8 @@ static int wpa_supplicant_validate_ie_ft(struct wpa_sm *sm,
if (sm->assoc_resp_ies) {
pos = sm->assoc_resp_ies;
end = pos + sm->assoc_resp_ies_len;
while (pos + 2 < end) {
if (pos + 2 + pos[1] > end)
while (end - pos > 2) {
if (2 + pos[1] > end - pos)
break;
switch (*pos) {
case WLAN_EID_MOBILITY_DOMAIN:

6
src/rsn_supp/wpa_ie.c
View file

@ -378,7 +378,7 @@ static int wpa_parse_generic(const u8 *pos, const u8 *end,
return 0;
}
if (pos + 1 + RSN_SELECTOR_LEN < end &&
if (1 + RSN_SELECTOR_LEN < end - pos &&
pos[1] >= RSN_SELECTOR_LEN + PMKID_LEN &&
RSN_SELECTOR_GET(pos + 2) == RSN_KEY_DATA_PMKID) {
ie->pmkid = pos + 2 + RSN_SELECTOR_LEN;
@ -491,13 +491,13 @@ int wpa_supplicant_parse_ies(const u8 *buf, size_t len,
int ret = 0;
os_memset(ie, 0, sizeof(*ie));
for (pos = buf, end = pos + len; pos + 1 < end; pos += 2 + pos[1]) {
for (pos = buf, end = pos + len; end - pos > 1; pos += 2 + pos[1]) {
if (pos[0] == 0xdd &&
((pos == buf + len - 1) || pos[1] == 0)) {
/* Ignore padding */
break;
}
if (pos + 2 + pos[1] > end) {
if (2 + pos[1] > end - pos) {
wpa_printf(MSG_DEBUG, "WPA: EAPOL-Key Key Data "
"underflow (ie=%d len=%d pos=%d)",
pos[0], pos[1], (int) (pos - buf));