8259843: initialize dli_fname array before calling dll_address_to_library_name

Reviewed-by: lucy, dholmes

Author: MBaesken

src/hotspot/os/bsd/os_bsd.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1557,6 +1557,7 @@ void os::jvm_path(char *buf, jint buflen) {
   }
 
   char dli_fname[MAXPATHLEN];
+  dli_fname[0] = '\0';
   bool ret = dll_address_to_library_name(
                                          CAST_FROM_FN_PTR(address, os::jvm_path),
                                          dli_fname, sizeof(dli_fname), NULL);

src/hotspot/os/linux/os_linux.cpp

@@ -2637,6 +2637,7 @@ void os::jvm_path(char *buf, jint buflen) {
   }
 
   char dli_fname[MAXPATHLEN];
+  dli_fname[0] = '\0';
   bool ret = dll_address_to_library_name(
                                          CAST_FROM_FN_PTR(address, os::jvm_path),
                                          dli_fname, sizeof(dli_fname), NULL);

src/hotspot/share/prims/nativeLookup.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -434,8 +434,10 @@ void* NativeLookup::dll_load(const methodHandle& method) {
     address current_entry = method->native_function();
 
     char dll_name[JVM_MAXPATHLEN];
+    dll_name[0] = '\0';
     int offset;
-    if (os::dll_address_to_library_name(current_entry, dll_name, sizeof(dll_name), &offset)) {
+    bool ret = os::dll_address_to_library_name(current_entry, dll_name, sizeof(dll_name), &offset);
+    if (ret && dll_name[0] != '\0') {
       char ebuf[32];
       return os::dll_load(dll_name, ebuf, sizeof(ebuf));
     }

src/hotspot/share/runtime/frame.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -540,9 +540,11 @@ void frame::print_C_frame(outputStream* st, char* buf, int buflen, address pc) {
   int offset;
   bool found;
 
+  if (buf == NULL || buflen < 1) return;
   // libname
+  buf[0] = '\0';
   found = os::dll_address_to_library_name(pc, buf, buflen, &offset);
-  if (found) {
+  if (found && buf[0] != '\0') {
     // skip directory names
     const char *p1, *p2;
     p1 = buf;