[PATCH v2 6/6] erp: Fix buffer overflow for 32 byte SSIDs

[Denis Kenzior <denkenz@gmail.com>]

ssid is declared as a 32 byte field in handshake_state, hence using it
as a string which is assumed to be nul-terminated will fail for SSIDs
that are 32 bytes long.

Fixes: d938d362b212 ("erp: ERP implementation and key cache move")
Fixes: 433373fe28a4 ("eapol: cache ERP keys on EAP success")
---
 src/eapol.c |  2 +-
 src/erp.c   | 10 ++++++++--
 src/erp.h   |  2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/eapol.c b/src/eapol.c
index 6fb2f3068f0b..3d7b3d38fbcd 100644
--- a/src/eapol.c
+++ b/src/eapol.c
@@ -2531,7 +2531,7 @@ static void eapol_eap_results_cb(const uint8_t *msk_data, size_t msk_len,
 	if (sm->handshake->support_fils && emsk_data && session_id)
 		erp_cache_add(eap_get_identity(sm->eap), session_id,
 				session_len, emsk_data, emsk_len,
-				(const char *)sm->handshake->ssid);
+				sm->handshake->ssid, sm->handshake->ssid_len);
 
 	return;
 
diff --git a/src/erp.c b/src/erp.c
index 2729cfc874b4..859233465e8b 100644
--- a/src/erp.c
+++ b/src/erp.c
@@ -160,13 +160,19 @@ static void erp_cache_entry_destroy(void *data)
 
 void erp_cache_add(const char *id, const void *session_id,
 			size_t session_len, const void *emsk, size_t emsk_len,
-			const char *ssid)
+			const uint8_t *ssid, size_t ssid_len)
 {
 	struct erp_cache_entry *entry;
 
 	if (!unlikely(id || session_id || emsk))
 		return;
 
+	if (!util_ssid_is_utf8(ssid_len, ssid))
+		return;
+
+	if (util_ssid_is_hidden(ssid_len, ssid))
+		return;
+
 	entry = l_new(struct erp_cache_entry, 1);
 
 	entry->id = l_strdup(id);
@@ -174,7 +180,7 @@ void erp_cache_add(const char *id, const void *session_id,
 	entry->emsk_len = emsk_len;
 	entry->session_id = l_memdup(session_id, session_len);
 	entry->session_len = session_len;
-	entry->ssid = l_strdup(ssid);
+	entry->ssid = l_strndup((char *) ssid, ssid_len);
 	entry->expire_time = l_time_offset(l_time_now(),
 					ERP_DEFAULT_KEY_LIFETIME_US);
 
diff --git a/src/erp.h b/src/erp.h
index d2c9da9624a8..e844aa8ebf90 100644
--- a/src/erp.h
+++ b/src/erp.h
@@ -43,7 +43,7 @@ const void *erp_get_rmsk(struct erp_state *erp, size_t *rmsk_len);
 
 void erp_cache_add(const char *id, const void *session_id, size_t session_len,
 			const void *emsk, size_t emsk_len,
-			const char *ssid);
+			const uint8_t *ssid, size_t ssid_len);
 
 void erp_cache_remove(const char *id);
 
-- 
2.42.0