The correct type for the size of a chunk of memory is size_t.

By using uint32, we have bugs on 64-bit platforms: callers passing in a size_t, will have their size truncated, potentially allocating a smaller
chunk than requested. There are a few places this happens, including on the
receiving ends of IPCs(!)

However, coversely, other callers of the API might directly assign the
memory chunk's length to uint32, leading to a different possible truncation
problem. This is guaraded against by limiting operations internally to
std::numeric_limits<uint32_t> in size for now.

There's some minor cascade effects that make the CL look larger than it is.

BUG=164678
Review URL: https://codereview.chromium.org/11446048

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175987 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 8 insertions, 2 deletions

diff --git a/base/shared_memory_win.cc b/base/shared_memory_win.cc
index b0fdafe3..877ccd7 100644
--- a/base/shared_memory_win.cc
+++ b/base/shared_memory_win.cc
@@ -70,7 +70,7 @@ void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   ::CloseHandle(handle);
 }
 
-bool SharedMemory::CreateAndMapAnonymous(uint32 size) {
+bool SharedMemory::CreateAndMapAnonymous(size_t size) {
   return CreateAnonymous(size) && Map(size);
 }
 
@@ -80,6 +80,9 @@ bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
   if (options.size == 0)
     return false;
 
+  if (options.size > static_cast<size_t>(std::numeric_limits<int>::max()))
+    return false;
+
   // NaCl's memory allocator requires 0mod64K alignment and size for
   // shared memory objects.  To allow passing shared memory to NaCl,
   // therefore we round the size actually created to the nearest 64K unit.
@@ -131,10 +134,13 @@ bool SharedMemory::Open(const std::string& name, bool read_only) {
   return false;
 }
 
-bool SharedMemory::Map(uint32 bytes) {
+bool SharedMemory::Map(size_t bytes) {
   if (mapped_file_ == NULL)
     return false;
 
+  if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
+    return false;
+
   memory_ = MapViewOfFile(mapped_file_,
       read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, 0, 0, bytes);
   if (memory_ != NULL) {