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RSN auth: 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 18:43:44 +03:00
parent a5a2f252cb
commit 1e72ba2e61
1 changed files with 5 additions and 5 deletions
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10
src/ap/wpa_auth_ie.c
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@ -251,7 +251,7 @@ int wpa_write_rsn_ie(struct wpa_auth_config *conf, u8 *buf, size_t len,
pos += 2; pos += 2;
if (pmkid) { if (pmkid) {
if (pos + 2 + PMKID_LEN > buf + len) if (2 + PMKID_LEN > buf + len - pos)
return -1; return -1;
/* PMKID Count */ /* PMKID Count */
WPA_PUT_LE16(pos, 1); WPA_PUT_LE16(pos, 1);
@ -263,7 +263,7 @@ int wpa_write_rsn_ie(struct wpa_auth_config *conf, u8 *buf, size_t len,
#ifdef CONFIG_IEEE80211W #ifdef CONFIG_IEEE80211W
if (conf->ieee80211w != NO_MGMT_FRAME_PROTECTION && if (conf->ieee80211w != NO_MGMT_FRAME_PROTECTION &&
conf->group_mgmt_cipher != WPA_CIPHER_AES_128_CMAC) { conf->group_mgmt_cipher != WPA_CIPHER_AES_128_CMAC) {
if (pos + 2 + 4 > buf + len) if (2 + 4 > buf + len - pos)
return -1; return -1;
if (pmkid == NULL) { if (pmkid == NULL) {
/* PMKID Count */ /* PMKID Count */
@ -791,7 +791,7 @@ static int wpa_parse_generic(const u8 *pos, const u8 *end,
return 0; return 0;
} }
if (pos + 1 + RSN_SELECTOR_LEN < end && if (1 + RSN_SELECTOR_LEN < end - pos &&
pos[1] >= RSN_SELECTOR_LEN + PMKID_LEN && pos[1] >= RSN_SELECTOR_LEN + PMKID_LEN &&
RSN_SELECTOR_GET(pos + 2) == RSN_KEY_DATA_PMKID) { RSN_SELECTOR_GET(pos + 2) == RSN_KEY_DATA_PMKID) {
ie->pmkid = pos + 2 + RSN_SELECTOR_LEN; ie->pmkid = pos + 2 + RSN_SELECTOR_LEN;
@ -887,13 +887,13 @@ int wpa_parse_kde_ies(const u8 *buf, size_t len, struct wpa_eapol_ie_parse *ie)
int ret = 0; int ret = 0;
os_memset(ie, 0, sizeof(*ie)); 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 && if (pos[0] == 0xdd &&
((pos == buf + len - 1) || pos[1] == 0)) { ((pos == buf + len - 1) || pos[1] == 0)) {
/* Ignore padding */ /* Ignore padding */
break; break;
} }
if (pos + 2 + pos[1] > end) { if (2 + pos[1] > end - pos) {
wpa_printf(MSG_DEBUG, "WPA: EAPOL-Key Key Data " wpa_printf(MSG_DEBUG, "WPA: EAPOL-Key Key Data "
"underflow (ie=%d len=%d pos=%d)", "underflow (ie=%d len=%d pos=%d)",
pos[0], pos[1], (int) (pos - buf)); pos[0], pos[1], (int) (pos - buf));