From 1aa1e2c8ccaae7848f64cd836e5d78f74fc814c2 Mon Sep 17 00:00:00 2001
From: Alexandre Abadie <alexandre.abadie@inria.fr>
Date: Sun, 27 Oct 2019 11:20:41 +0100
Subject: [PATCH] sys/net/nanocoap: return ENOENT if parsing option failed

This fixes a potential use of uninitialized len in subsequent function calls.

This was reported by scan-build
---
 sys/include/net/nanocoap.h                    | 1 +
 sys/net/application_layer/nanocoap/nanocoap.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/sys/include/net/nanocoap.h b/sys/include/net/nanocoap.h
index 9158f85578..b469f511bc 100644
--- a/sys/include/net/nanocoap.h
+++ b/sys/include/net/nanocoap.h
@@ -586,6 +586,7 @@ ssize_t coap_opt_get_next(const coap_pkt_t *pkt, coap_optpos_t *opt,
  *
  * @return        length of option; 0 if the option exists but is empty
  * @return        -ENOENT if option not found
+ * @return        -EINVAL if option cannot be parsed
  */
 ssize_t coap_opt_get_opaque(coap_pkt_t *pkt, unsigned opt_num, uint8_t **value);
 /**@}*/
diff --git a/sys/net/application_layer/nanocoap/nanocoap.c b/sys/net/application_layer/nanocoap/nanocoap.c
index df0853c349..904888cf09 100644
--- a/sys/net/application_layer/nanocoap/nanocoap.c
+++ b/sys/net/application_layer/nanocoap/nanocoap.c
@@ -217,6 +217,10 @@ ssize_t coap_opt_get_opaque(coap_pkt_t *pkt, unsigned opt_num, uint8_t **value)
     int len;
 
     *value = _parse_option(pkt, start, &delta, &len);
+    if (!*value) {
+        return -EINVAL;
+    }
+
     return len;
 }