From d4585e7470163c794025c2d56930c0e5a5fbae3c Mon Sep 17 00:00:00 2001
From: Alan Wu <XrXr@users.noreply.github.com>
Date: Thu, 3 Sep 2020 15:51:14 -0400
Subject: [PATCH] Avoid potential for rb_raise() while crashing

rb_obj_raw_info is called while printing out crash messages and
sometimes called during garbage collection. Calling rb_raise() in these
situations is undesirable because it can start executing ensure blocks.
---
 gc.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/gc.c b/gc.c
index 535f526391..99c79fe10c 100644
--- a/gc.c
+++ b/gc.c
@@ -11702,6 +11702,15 @@ rb_raw_iseq_info(char *buff, const int buff_size, const rb_iseq_t *iseq)
 
 bool rb_ractor_p(VALUE rv);
 
+static int
+str_len_no_raise(VALUE str)
+{
+    long len = RSTRING_LEN(str);
+    if (len < 0) return 0;
+    if (len > INT_MAX) return INT_MAX;
+    return (int)len;
+}
+
 const char *
 rb_raw_obj_info(char *buff, const int buff_size, VALUE obj)
 {
@@ -11789,7 +11798,7 @@ rb_raw_obj_info(char *buff, const int buff_size, VALUE obj)
             }
 	    break;
 	  case T_STRING: {
-            APPENDF((BUFF_ARGS, "%.*s", RSTRING_LENINT(obj), RSTRING_PTR(obj)));
+            APPENDF((BUFF_ARGS, "%.*s", str_len_no_raise(obj), RSTRING_PTR(obj)));
 	    break;
 	  }
           case T_MOVED: {