Fix potential null pointer dereference.

src/processor/minidump.cc

 // Copyright (c) 2010 Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 3981 matching lines @@
 // MinidumpLinuxMapsList
 //
 
 MinidumpLinuxMapsList::MinidumpLinuxMapsList(Minidump *minidump)
     : MinidumpStream(minidump),
       maps_(NULL),
       maps_count_(0) {
 }
 
 MinidumpLinuxMapsList::~MinidumpLinuxMapsList() {
-  for (unsigned int i = 0; i < maps_->size(); i++) {
-    delete (*maps_)[i];
+  if (maps_) {
+    for (unsigned int i = 0; i < maps_->size(); i++) {
+      delete (*maps_)[i];
+    }
+    delete maps_;
   }
-  delete maps_;
 }
 
 const MinidumpLinuxMaps *MinidumpLinuxMapsList::GetLinuxMapsForAddress(
     uint64_t address) const {
-  if (!valid_) {
+  if (!valid_ || (maps_ == NULL)) {
     BPLOG(ERROR) << "Invalid MinidumpLinuxMapsList for GetLinuxMapsForAddress";
     return NULL;
   }
 
   // Search every memory mapping.
   for (unsigned int index = 0; index < maps_count_; index++) {
     // Check if address is within bounds of the current memory region.
     if ((*maps_)[index]->GetBase() <= address &&
         (*maps_)[index]->GetBase() + (*maps_)[index]->GetSize() > address) {
       return (*maps_)[index];
     }
   }
 
   // No mapping encloses the memory address.
   BPLOG(ERROR) << "MinidumpLinuxMapsList has no mapping at "
                << HexString(address);
   return NULL;
 }
 
 const MinidumpLinuxMaps *MinidumpLinuxMapsList::GetLinuxMapsAtIndex(
     unsigned int index) const {
-  if (!valid_) {
+  if (!valid_ || (maps_ == NULL)) {
     BPLOG(ERROR) << "Invalid MinidumpLinuxMapsList for GetLinuxMapsAtIndex";
     return NULL;
   }
 
   // Index out of bounds.
-  if (index >= maps_count_) {
+  if (index >= maps_count_ || (maps_ == NULL)) {
     BPLOG(ERROR) << "MinidumpLinuxMapsList index of out range: "
                  << index
                  << "/"
                  << maps_count_;
     return NULL;
   }
   return (*maps_)[index];
 }
 
 bool MinidumpLinuxMapsList::Read(uint32_t expected_size) {
   // Invalidate cached data.
-  delete maps_;
+  if (maps_) {
+    for (unsigned int i = 0; i < maps_->size(); i++) {
+      delete (*maps_)[i];
+    }
+    delete maps_;
+  }
   maps_ = NULL;
   maps_count_ = 0;
 
   valid_ = false;
 
   // Load and check expected stream length.
   uint32_t length = 0;
   if (!minidump_->SeekToStreamType(MD_LINUX_MAPS, &length)) {
     BPLOG(ERROR) << "MinidumpLinuxMapsList stream type not found";
     return false;
@@ skipping 32 matching lines @@
   }
 
   // Set instance variables.
   maps_ = maps.release();
   maps_count_ = maps_->size();
   valid_ = true;
   return true;
 }
 
 void MinidumpLinuxMapsList::Print() {
-  if (!valid_) {
+  if (!valid_ || (maps_ == NULL)) {
     BPLOG(ERROR) << "MinidumpLinuxMapsList cannot print valid data";
     return;
   }
   for (size_t i = 0; i < maps_->size(); i++) {
     (*maps_)[i]->Print();
   }
 }
 
 //
 // Minidump
@@ skipping 649 matching lines @@
     return NULL;
   }
 
   *stream = new_stream.release();
   info->stream = *stream;
   return *stream;
 }
 
 
 }  // namespace google_breakpad