wifi: cfg80211: ensure length byte is present before access

When iterating the elements here, ensure the length byte is
present before checking it to see if the entire element will
fit into the buffer.

Longer term, we should rewrite this code using the type-safe
element iteration macros that check all of this.

Fixes: 0b8fb8235b ("cfg80211: Parsing of Multiple BSSID information in scanning")
Reported-by: Soenke Huster <shuster@seemoo.tu-darmstadt.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2022-09-29 21:50:44 +02:00
parent ff05d4b45d
commit 567e14e39e

View file

@ -304,7 +304,8 @@ static size_t cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
tmp_old = cfg80211_find_ie(WLAN_EID_SSID, ie, ielen);
tmp_old = (tmp_old) ? tmp_old + tmp_old[1] + 2 : ie;
while (tmp_old + tmp_old[1] + 2 - ie <= ielen) {
while (tmp_old + 2 - ie <= ielen &&
tmp_old + tmp_old[1] + 2 - ie <= ielen) {
if (tmp_old[0] == 0) {
tmp_old++;
continue;
@ -364,7 +365,8 @@ static size_t cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
* copied to new ie, skip ssid, capability, bssid-index ie
*/
tmp_new = sub_copy;
while (tmp_new + tmp_new[1] + 2 - sub_copy <= subie_len) {
while (tmp_new + 2 - sub_copy <= subie_len &&
tmp_new + tmp_new[1] + 2 - sub_copy <= subie_len) {
if (!(tmp_new[0] == WLAN_EID_NON_TX_BSSID_CAP ||
tmp_new[0] == WLAN_EID_SSID)) {
memcpy(pos, tmp_new, tmp_new[1] + 2);