Fix integer overflow in URI parsing

If an ID exeeds the max. possible value we return early with an error
instead of continuing and checking for too big values at the end.

Author: LukasWoodtli

core/uri.c

@@ -71,6 +71,9 @@ static int prv_parseNumber(uint8_t * uriString,
         {
             result *= 10;
             result += uriString[*headP] - '0';
+            if (result > LWM2M_MAX_ID) {
+                return -1;
+            }
         }
         else
         {

fuzzing/registration_handleRequest/CMakeLists.txt

@@ -1,3 +1,7 @@
-add_fuzzing_test(TARGET_NAME fuz_registration_handleRequest SOURCE_FILES fuz_registration_handleRequest.c)
+add_fuzzing_test(
+    TARGET_NAME fuz_registration_handleRequest
+    SOURCE_FILES fuz_registration_handleRequest.c
+    CRASH_FILES_DIR crash_files/
+)
 # workaround to be able to test private functions
 target_include_directories(fuz_registration_handleRequest PRIVATE ../../coap ../../core)

fuzzing/registration_handleRequest/crash_files/crash-4e842fc818f746482a3bfd0029ed4b5ed5b044d3

@@ -0,0 +1 @@
+</37777777777>/>/