65 lines
2.5 KiB
Diff
65 lines
2.5 KiB
Diff
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Original patch copied from http://w1.fi/security/2015-5/
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and then backported to wpa-supplicant-2.4.
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From df9079e72760ceb7ebe7fb11538200c516bdd886 Mon Sep 17 00:00:00 2001
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From: Jouni Malinen <j@w1.fi>
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Date: Tue, 7 Jul 2015 21:57:28 +0300
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Subject: [PATCH] NFC: Fix payload length validation in NDEF record parser
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It was possible for the 32-bit record->total_length value to end up
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wrapping around due to integer overflow if the longer form of payload
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length field is used and record->payload_length gets a value close to
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2^32. This could result in ndef_parse_record() accepting a too large
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payload length value and the record type filter reading up to about 20
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bytes beyond the end of the buffer and potentially killing the process.
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This could also result in an attempt to allocate close to 2^32 bytes of
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heap memory and if that were to succeed, a buffer read overflow of the
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same length which would most likely result in the process termination.
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In case of record->total_length ending up getting the value 0, there
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would be no buffer read overflow, but record parsing would result in an
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infinite loop in ndef_parse_records().
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Any of these error cases could potentially be used for denial of service
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attacks over NFC by using a malformed NDEF record on an NFC Tag or
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sending them during NFC connection handover if the application providing
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the NDEF message to hostapd/wpa_supplicant did no validation of the
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received records. While such validation is likely done in the NFC stack
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that needs to parse the NFC messages before further processing,
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hostapd/wpa_supplicant better be prepared for any data being included
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here.
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Fix this by validating record->payload_length value in a way that
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detects integer overflow. (CID 122668)
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Signed-off-by: Jouni Malinen <j@w1.fi>
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---
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src/wps/ndef.c | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/src/wps/ndef.c b/src/wps/ndef.c
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index 5604b0a..50d018f 100644
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--- a/src/wps/ndef.c
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+++ b/src/wps/ndef.c
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@@ -48,6 +48,8 @@ static int ndef_parse_record(const u8 *data, u32 size,
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if (size < 6)
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return -1;
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record->payload_length = ntohl(*(u32 *)pos);
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+ if (record->payload_length > size - 6)
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+ return -1;
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pos += sizeof(u32);
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}
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@@ -68,7 +70,8 @@ static int ndef_parse_record(const u8 *data, u32 size,
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pos += record->payload_length;
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record->total_length = pos - data;
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- if (record->total_length > size)
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+ if (record->total_length > size ||
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+ record->total_length < record->payload_length)
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return -1;
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return 0;
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}
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--
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1.9.1
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