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: 0b8fb82 ("cfg80211: Parsing of Multiple BSSID information in scanning") Reported-by: Soenke Huster <[email protected]> Signed-off-by: Johannes Berg <[email protected]>
josf · Oct 10, 2022 · 567e14e · 567e14e
1 parent ff05d4b
commit 567e14e
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
@@ -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);