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/fencedMemory.hpp"
  26 
  27 #include "memory/allocation.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "runtime/os.hpp"
  30 
  31 void* FencedMemory::wrap_copy(const void* ptr, const size_t len, const void* tag) {
  32   size_t total_sz = FencedMemory::get_total_size(len);
  33   void* outerp = os::malloc(total_sz, mtInternal);
  34   if (outerp != NULL) {
  35     FencedMemory fenced(outerp, len, tag);
  36     void* innerp = fenced.get_user_ptr();
  37     memcpy(innerp, ptr, len);
  38     return innerp;
  39   }
  40   return NULL; // OOM
  41 }
  42 
  43 bool FencedMemory::free_copy(void* p) {
  44   if (p == NULL) {
  45     return true;
  46   }
  47   FencedMemory fenced((u_char*)p);
  48   bool verify_ok = fenced.verify_fences();
  49 
  50   /* always attempt to free, pass problem on to any nested memchecker */
  51   os::free(fenced.release_for_freeing());
  52 
  53   return verify_ok;
  54 }
  55 
  56 void FencedMemory::print_on(outputStream* st) const {
  57   if (_base_addr == NULL) {
  58     st->print_cr("FencedMemory(" INTPTR_FORMAT ") not associated to any memory", this);
  59     return;
  60   }
  61   st->print_cr("FencedMemory(" INTPTR_FORMAT ") base_addr=" PTR_FORMAT
  62       " tag=" PTR_FORMAT " user_size=" SIZE_FORMAT " user_data=" PTR_FORMAT,
  63       this, _base_addr, get_tag(), get_user_size(), get_user_ptr());
  64 
  65   Fence* fence = get_head_fence();
  66   st->print_cr("  Header fence @" PTR_FORMAT " is %s", fence, (fence->verify() ? "OK" : "BROKEN"));
  67   fence = get_tail_fence();
  68   st->print_cr("  Trailer fence @" PTR_FORMAT " is %s", fence, (fence->verify() ? "OK" : "BROKEN"));
  69 
  70   u_char udata = *get_user_ptr();
  71   switch (udata) {
  72   case uninitBlockPad:
  73     st->print_cr("  User data appears unused");
  74     break;
  75   case freeBlockPad:
  76     st->print_cr("  User data appears to have been freed");
  77     break;
  78   default:
  79     st->print_cr("  User data appears to be in use");
  80   }
  81 }
  82 
  83 // test code...
  84 
  85 #ifndef PRODUCT
  86 
  87 static void fenced_memory_test_check(void* p, size_t sz, void* tag) {
  88   assert(p, "NULL pointer given to check");
  89   u_char* c = (u_char*) p;
  90   FencedMemory fenced(c);
  91   assert(fenced.get_tag() == tag, "Tag is not the same as supplied");
  92   assert(fenced.get_user_ptr() == c, "User pointer is not the same as supplied");
  93   assert(fenced.get_user_size() == sz, "User size is not the same as supplied");
  94   assert(fenced.verify_fences(), "Fence broken");
  95 }
  96 
  97 void FencedMemory::test_fenced_memory() {
  98   // Test the basic characteristics...
  99   size_t total_sz = FencedMemory::get_total_size(1);
 100   assert(total_sz > 1 && total_sz >= (sizeof(FenceHeader) + 1 + sizeof(Fence)), "Unexpected size");
 101   u_char* basep = (u_char*) os::malloc(total_sz, mtInternal);
 102 
 103   FencedMemory fenced(basep, 1, (void*)0xf000f000);
 104 
 105   assert(*basep == badResourceValue, "Expected fence in the form of badResourceValue");
 106   u_char* userp = fenced.get_user_ptr();
 107   assert(*userp == uninitBlockPad, "Expected uninitialized data in the form of uninitBlockPad");
 108   fenced_memory_test_check(userp, 1, (void*)0xf000f000);
 109 
 110   void* freep = fenced.release_for_freeing();
 111   assert((u_char*)freep == basep, "Expected the same pointer fence was ");
 112   assert(*userp == freeBlockPad, "Expected user data to be free block padded");
 113   assert(!fenced.verify_fences(), "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(FencedMemory::get_total_size(sz), mtInternal);
 120     void* up = fenced.wrap_with_fences(p, sz, (void*)1);
 121     memset(up, 0, sz);
 122     fenced_memory_test_check(up, sz, (void*)1);
 123     os::free(fenced.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(FencedMemory::get_total_size(1), mtInternal);
 129   fenced.wrap_with_fences(basep, 1);
 130   *basep = 0;
 131   assert(!fenced.verify_fences(), "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(FencedMemory::get_total_size(sz), mtInternal);
 138     void* up = fenced.wrap_with_fences(p, sz, (void*)1);
 139     memset(up, 0, sz + 1); // Buffer-overwrite (within fence)
 140     assert(!fenced.verify_fences(), "Fence was not broken as expected");
 141     os::free(fenced.release_for_freeing());
 142     sz = (sz << 4) + 1;
 143   } while (sz < (256 * 1024));
 144 
 145   // Test wrap_copy/wrap_free...
 146   assert(FencedMemory::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*) FencedMemory::wrap_copy(str, str_sz);
 151   fenced_memory_test_check(str_copy, str_sz, NULL);
 152   assert(strcmp(str, str_copy) == 0, "Not identical copy");
 153   assert(FencedMemory::free_copy(str_copy), "Free copy failed to verify");
 154 
 155   void* no_data = NULL;
 156   void* no_data_copy = FencedMemory::wrap_copy(no_data, 0);
 157   assert(FencedMemory::free_copy(no_data_copy), "Expected valid fences even for no data copy");
 158 }
 159 
 160 #endif // !PRODUCT
 161