From 7a319cd96f7f4869300b32442ebe892ae557f41c Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Mon, 8 Feb 2016 15:47:49 +0100
Subject: erts: Fix error cases in enif_get_list_length

false if improper list
false if length > UINT_MAX
---
 erts/emulator/beam/erl_nif.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

(limited to 'erts/emulator/beam/erl_nif.c')

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index b057ec7770..12aaf4ce53 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -911,8 +911,13 @@ int enif_get_list_cell(ErlNifEnv* env, Eterm term, Eterm* head, Eterm* tail)
 
 int enif_get_list_length(ErlNifEnv* env, Eterm term, unsigned* len)
 {
-    if (is_not_list(term) && is_not_nil(term)) return 0;
-    *len = erts_list_length(term);
+    Sint i;
+    Uint u;
+
+    if ((i = erts_list_length(term)) < 0) return 0;
+    u = (Uint)i;
+    if ((unsigned)u != u) return 0;
+    *len = u;
     return 1;
 }
 
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