path: root/src/wps
diff options
authorJouni Malinen <j@w1.fi>2015-07-07 18:57:28 (GMT)
committerJouni Malinen <j@w1.fi>2015-07-08 13:52:25 (GMT)
commitdf9079e72760ceb7ebe7fb11538200c516bdd886 (patch)
tree43cc8b1900ba8dfd53edc0a19aab49a6cb2b4fd7 /src/wps
parentb843a8b8a6150d1364efb7d9c05bec913b65c3bd (diff)
NFC: Fix payload length validation in NDEF record parser
It was possible for the 32-bit record->total_length value to end up wrapping around due to integer overflow if the longer form of payload length field is used and record->payload_length gets a value close to 2^32. This could result in ndef_parse_record() accepting a too large payload length value and the record type filter reading up to about 20 bytes beyond the end of the buffer and potentially killing the process. This could also result in an attempt to allocate close to 2^32 bytes of heap memory and if that were to succeed, a buffer read overflow of the same length which would most likely result in the process termination. In case of record->total_length ending up getting the value 0, there would be no buffer read overflow, but record parsing would result in an infinite loop in ndef_parse_records(). Any of these error cases could potentially be used for denial of service attacks over NFC by using a malformed NDEF record on an NFC Tag or sending them during NFC connection handover if the application providing the NDEF message to hostapd/wpa_supplicant did no validation of the received records. While such validation is likely done in the NFC stack that needs to parse the NFC messages before further processing, hostapd/wpa_supplicant better be prepared for any data being included here. Fix this by validating record->payload_length value in a way that detects integer overflow. (CID 122668) Signed-off-by: Jouni Malinen <j@w1.fi>
Diffstat (limited to 'src/wps')
1 files changed, 4 insertions, 1 deletions
diff --git a/src/wps/ndef.c b/src/wps/ndef.c
index 5604b0a..50d018f 100644
--- a/src/wps/ndef.c
+++ b/src/wps/ndef.c
@@ -48,6 +48,8 @@ static int ndef_parse_record(const u8 *data, u32 size,
if (size < 6)
return -1;
record->payload_length = WPA_GET_BE32(pos);
+ if (record->payload_length > size - 6)
+ return -1;
pos += sizeof(u32);
@@ -68,7 +70,8 @@ static int ndef_parse_record(const u8 *data, u32 size,
pos += record->payload_length;
record->total_length = pos - data;
- if (record->total_length > size)
+ if (record->total_length > size ||
+ record->total_length < record->payload_length)
return -1;
return 0;