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Avoid undefined behavior in pointer arithmetic in scan result IE parsing

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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 11:52:32 +03:00
parent bdce45b83e
commit 904e977bc7
1 changed files with 8 additions and 8 deletions
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16
wpa_supplicant/scan.c
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@ -1521,8 +1521,8 @@ const u8 * wpa_scan_get_ie(const struct wpa_scan_res *res, u8 ie)
pos = (const u8 *) (res + 1); pos = (const u8 *) (res + 1);
end = pos + res->ie_len; end = pos + res->ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == ie) if (pos[0] == ie)
return pos; return pos;
@ -1550,8 +1550,8 @@ const u8 * wpa_scan_get_vendor_ie(const struct wpa_scan_res *res,
pos = (const u8 *) (res + 1); pos = (const u8 *) (res + 1);
end = pos + res->ie_len; end = pos + res->ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))
@ -1587,8 +1587,8 @@ const u8 * wpa_scan_get_vendor_ie_beacon(const struct wpa_scan_res *res,
pos += res->ie_len; pos += res->ie_len;
end = pos + res->beacon_ie_len; end = pos + res->beacon_ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))
@ -1623,8 +1623,8 @@ struct wpabuf * wpa_scan_get_vendor_ie_multi(const struct wpa_scan_res *res,
pos = (const u8 *) (res + 1); pos = (const u8 *) (res + 1);
end = pos + res->ie_len; end = pos + res->ie_len;
while (pos + 1 < end) { while (end - pos > 1) {
if (pos + 2 + pos[1] > end) if (2 + pos[1] > end - pos)
break; break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 && if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2])) vendor_type == WPA_GET_BE32(&pos[2]))