From 1a554a300d73489213c137776c1da69b074303f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vivek=20Das=C2=A0Mohapatra?= <vivek@collabora.com>
Date: Sat, 5 Oct 2024 03:19:29 +0100
Subject: [PATCH] mpdu: tolerate technically illegal but harmless cloned IEs

---
 src/ie.h   | 17 +++++++++++++++++
 src/mpdu.c |  7 +++++++
 2 files changed, 24 insertions(+)

diff --git a/src/ie.h b/src/ie.h
index 4498785a..bc750696 100644
--- a/src/ie.h
+++ b/src/ie.h
@@ -598,6 +598,23 @@ static inline const unsigned char *ie_tlv_iter_get_data(
 	return iter->data;
 }
 
+static inline bool ie_tlv_iter_data_eq(struct ie_tlv_iter *a,
+					struct ie_tlv_iter *b)
+{
+	if (a == b)
+		return true;
+
+	if (a == NULL || b == NULL)
+		return false;
+
+	if (ie_tlv_iter_get_length(a) != ie_tlv_iter_get_length(b))
+		return false;
+
+	return memcmp(ie_tlv_iter_get_data(a),
+			ie_tlv_iter_get_data(b),
+			ie_tlv_iter_get_length(a)) == 0;
+}
+
 void *ie_tlv_extract_wsc_payload(const uint8_t *ies, size_t len,
 							ssize_t *out_len);
 void *ie_tlv_encapsulate_wsc_payload(const uint8_t *data, size_t len,
diff --git a/src/mpdu.c b/src/mpdu.c
index 9d0409d2..f55866e1 100644
--- a/src/mpdu.c
+++ b/src/mpdu.c
@@ -398,9 +398,16 @@ static bool validate_mgmt_ies(const uint8_t *ies, size_t ies_len,
 
 			memcpy(&clone, &iter, sizeof(clone));
 
+			/*
+			 * Some APs send completely identical duplicate IEs:
+			 * Since these are harmless (and ignored by us) we're
+			 * going to allow them here for interoperability.
+			 */
 			while (ie_tlv_iter_next(&clone)) {
 				if (ie_tlv_iter_get_tag(&clone) != tag)
 					continue;
+				else if (ie_tlv_iter_data_eq(&iter, &clone))
+					continue;
 
 				return false;
 			}