1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 #include "precompiled.hpp"
  25 #include "memory/allocation.hpp"
  26 #include "memory/allocation.inline.hpp"
  27 #include "memory/guardedMemory.hpp"
  28 #include "runtime/os.hpp"
  29 
  30 void* GuardedMemory::wrap_copy(const void* ptr, const size_t len, const void* tag) {
  31   size_t total_sz = GuardedMemory::get_total_size(len);
  32   void* outerp = os::malloc(total_sz, mtInternal);
  33   if (outerp != NULL) {
  34     GuardedMemory guarded(outerp, len, tag);
  35     void* innerp = guarded.get_user_ptr();
  36     memcpy(innerp, ptr, len);
  37     return innerp;
  38   }
  39   return NULL; // OOM
  40 }
  41 
  42 bool GuardedMemory::free_copy(void* p) {
  43   if (p == NULL) {
  44     return true;
  45   }
  46   GuardedMemory guarded((u_char*)p);
  47   bool verify_ok = guarded.verify_guards();
  48 
  49   /* always attempt to free, pass problem on to any nested memchecker */
  50   os::free(guarded.release_for_freeing());
  51 
  52   return verify_ok;
  53 }
  54 
  55 void GuardedMemory::print_on(outputStream* st) const {
  56   if (_base_addr == NULL) {
  57     st->print_cr("GuardedMemory(" PTR_FORMAT ") not associated to any memory", p2i(this));
  58     return;
  59   }
  60   st->print_cr("GuardedMemory(" PTR_FORMAT ") base_addr=" PTR_FORMAT
  61       " tag=" PTR_FORMAT " user_size=" SIZE_FORMAT " user_data=" PTR_FORMAT,
  62       p2i(this), p2i(_base_addr), p2i(get_tag()), get_user_size(), p2i(get_user_ptr()));
  63 
  64   Guard* guard = get_head_guard();
  65   st->print_cr("  Header guard @" PTR_FORMAT " is %s", p2i(guard), (guard->verify() ? "OK" : "BROKEN"));
  66   guard = get_tail_guard();
  67   st->print_cr("  Trailer guard @" PTR_FORMAT " is %s", p2i(guard), (guard->verify() ? "OK" : "BROKEN"));
  68 
  69   u_char udata = *get_user_ptr();
  70   switch (udata) {
  71   case uninitBlockPad:
  72     st->print_cr("  User data appears unused");
  73     break;
  74   case freeBlockPad:
  75     st->print_cr("  User data appears to have been freed");
  76     break;
  77   default:
  78     st->print_cr("  User data appears to be in use");
  79     break;
  80   }
  81 }
  82 
  83 // test code...
  84 
  85 #ifndef PRODUCT
  86 
  87 static void guarded_memory_test_check(void* p, size_t sz, void* tag) {
  88   assert(p != NULL, "NULL pointer given to check");
  89   u_char* c = (u_char*) p;
  90   GuardedMemory guarded(c);
  91   assert(guarded.get_tag() == tag, "Tag is not the same as supplied");
  92   assert(guarded.get_user_ptr() == c, "User pointer is not the same as supplied");
  93   assert(guarded.get_user_size() == sz, "User size is not the same as supplied");
  94   assert(guarded.verify_guards(), "Guard broken");
  95 }
  96 
  97 void GuardedMemory::test_guarded_memory() {
  98   // Test the basic characteristics...
  99   size_t total_sz = GuardedMemory::get_total_size(1);
 100   assert(total_sz > 1 && total_sz >= (sizeof(GuardHeader) + 1 + sizeof(Guard)), "Unexpected size");
 101   u_char* basep = (u_char*) os::malloc(total_sz, mtInternal);
 102 
 103   GuardedMemory guarded(basep, 1, (void*)0xf000f000);
 104 
 105   assert(*basep == badResourceValue, "Expected guard in the form of badResourceValue");
 106   u_char* userp = guarded.get_user_ptr();
 107   assert(*userp == uninitBlockPad, "Expected uninitialized data in the form of uninitBlockPad");
 108   guarded_memory_test_check(userp, 1, (void*)0xf000f000);
 109 
 110   void* freep = guarded.release_for_freeing();
 111   assert((u_char*)freep == basep, "Expected the same pointer guard was ");
 112   assert(*userp == freeBlockPad, "Expected user data to be free block padded");
 113   assert(!guarded.verify_guards(), "Expected failed");
 114   os::free(freep);
 115 
 116   // Test a number of odd sizes...
 117   size_t sz = 0;
 118   do {
 119     void* p = os::malloc(GuardedMemory::get_total_size(sz), mtInternal);
 120     void* up = guarded.wrap_with_guards(p, sz, (void*)1);
 121     memset(up, 0, sz);
 122     guarded_memory_test_check(up, sz, (void*)1);
 123     os::free(guarded.release_for_freeing());
 124     sz = (sz << 4) + 1;
 125   } while (sz < (256 * 1024));
 126 
 127   // Test buffer overrun into head...
 128   basep = (u_char*) os::malloc(GuardedMemory::get_total_size(1), mtInternal);
 129   guarded.wrap_with_guards(basep, 1);
 130   *basep = 0;
 131   assert(!guarded.verify_guards(), "Expected failure");
 132   os::free(basep);
 133 
 134   // Test buffer overrun into tail with a number of odd sizes...
 135   sz = 1;
 136   do {
 137     void* p = os::malloc(GuardedMemory::get_total_size(sz), mtInternal);
 138     void* up = guarded.wrap_with_guards(p, sz, (void*)1);
 139     memset(up, 0, sz + 1); // Buffer-overwrite (within guard)
 140     assert(!guarded.verify_guards(), "Guard was not broken as expected");
 141     os::free(guarded.release_for_freeing());
 142     sz = (sz << 4) + 1;
 143   } while (sz < (256 * 1024));
 144 
 145   // Test wrap_copy/wrap_free...
 146   assert(GuardedMemory::free_copy(NULL), "Expected free NULL to be OK");
 147 
 148   const char* str = "Check my bounds out";
 149   size_t str_sz = strlen(str) + 1;
 150   char* str_copy = (char*) GuardedMemory::wrap_copy(str, str_sz);
 151   guarded_memory_test_check(str_copy, str_sz, NULL);
 152   assert(strcmp(str, str_copy) == 0, "Not identical copy");
 153   assert(GuardedMemory::free_copy(str_copy), "Free copy failed to verify");
 154 
 155   void* no_data = NULL;
 156   void* no_data_copy = GuardedMemory::wrap_copy(no_data, 0);
 157   assert(GuardedMemory::free_copy(no_data_copy), "Expected valid guards even for no data copy");
 158 }
 159 
 160 #endif // !PRODUCT
 161