Memmap: Replace GetPointer with GetSpanForAddress

To ensure memory safety, callers of GetPointer have to perform a bounds
check. But how is this bounds check supposed to be performed?
GetPointerForRange contained one implementation of a bounds check, but
it was cumbersome, and it also isn't obvious why it's correct.

To make doing the right thing easier, this commit changes GetPointer to
return a span that tells the caller how many bytes it's allowed to
access.

1 files changed, 13 insertions, 4 deletions

diff --git a/Source/Core/VideoCommon/VertexLoaderManager.cpp b/Source/Core/VideoCommon/VertexLoaderManager.cpp
index 8ae9a9aa46..0c48bf32a8 100644
--- a/Source/Core/VideoCommon/VertexLoaderManager.cpp
+++ b/Source/Core/VideoCommon/VertexLoaderManager.cpp
@@ -91,26 +91,35 @@ void UpdateVertexArrayPointers()
   // Note: Only array bases 0 through 11 are used by the Vertex loaders.
   //       12 through 15 are used for loading data into xfmem.
   // We also only update the array base if the vertex description states we are going to use it.
+  // TODO: For memory safety, we need to check the sizes returned by GetSpanForAddress
   if (IsIndexed(g_main_cp_state.vtx_desc.low.Position))
+  {
     cached_arraybases[CPArray::Position] =
-        memory.GetPointer(g_main_cp_state.array_bases[CPArray::Position]);
+        memory.GetSpanForAddress(g_main_cp_state.array_bases[CPArray::Position]).data();
+  }
 
   if (IsIndexed(g_main_cp_state.vtx_desc.low.Normal))
+  {
     cached_arraybases[CPArray::Normal] =
-        memory.GetPointer(g_main_cp_state.array_bases[CPArray::Normal]);
+        memory.GetSpanForAddress(g_main_cp_state.array_bases[CPArray::Normal]).data();
+  }
 
   for (u8 i = 0; i < g_main_cp_state.vtx_desc.low.Color.Size(); i++)
   {
     if (IsIndexed(g_main_cp_state.vtx_desc.low.Color[i]))
+    {
       cached_arraybases[CPArray::Color0 + i] =
-          memory.GetPointer(g_main_cp_state.array_bases[CPArray::Color0 + i]);
+          memory.GetSpanForAddress(g_main_cp_state.array_bases[CPArray::Color0 + i]).data();
+    }
   }
 
   for (u8 i = 0; i < g_main_cp_state.vtx_desc.high.TexCoord.Size(); i++)
   {
     if (IsIndexed(g_main_cp_state.vtx_desc.high.TexCoord[i]))
+    {
       cached_arraybases[CPArray::TexCoord0 + i] =
-          memory.GetPointer(g_main_cp_state.array_bases[CPArray::TexCoord0 + i]);
+          memory.GetSpanForAddress(g_main_cp_state.array_bases[CPArray::TexCoord0 + i]).data();
+    }
   }
 
   g_bases_dirty = false;