kernel/thread: Fix potential crashes introduced in 26de4bb521b1ace7af76eff4f6956cb23ac0d58c

This amends cases where crashes can occur that were missed due to the
odd way the previous code was set up (using 3DS memory regions that
don't exist).

1 files changed, 25 insertions, 13 deletions

diff --git a/src/core/hle/kernel/shared_memory.cpp b/src/core/hle/kernel/shared_memory.cpp
index b3ddebb3d..21ddc2f7d 100644
--- a/src/core/hle/kernel/shared_memory.cpp
+++ b/src/core/hle/kernel/shared_memory.cpp
@@ -28,20 +28,32 @@ SharedPtr<SharedMemory> SharedMemory::Create(SharedPtr<Process> owner_process, u
     shared_memory->permissions = permissions;
     shared_memory->other_permissions = other_permissions;
 
-    auto& vm_manager = shared_memory->owner_process->vm_manager;
-
-    // The memory is already available and mapped in the owner process.
-    auto vma = vm_manager.FindVMA(address);
-    ASSERT_MSG(vma != vm_manager.vma_map.end(), "Invalid memory address");
-    ASSERT_MSG(vma->second.backing_block, "Backing block doesn't exist for address");
-
-    // The returned VMA might be a bigger one encompassing the desired address.
-    auto vma_offset = address - vma->first;
-    ASSERT_MSG(vma_offset + size <= vma->second.size,
-               "Shared memory exceeds bounds of mapped block");
+    if (address == 0) {
+        shared_memory->backing_block = std::make_shared<std::vector<u8>>(size);
+        shared_memory->backing_block_offset = 0;
+
+        // Refresh the address mappings for the current process.
+        if (Core::CurrentProcess() != nullptr) {
+            Core::CurrentProcess()->vm_manager.RefreshMemoryBlockMappings(
+                shared_memory->backing_block.get());
+        }
+    } else {
+        auto& vm_manager = shared_memory->owner_process->vm_manager;
+
+        // The memory is already available and mapped in the owner process.
+        auto vma = vm_manager.FindVMA(address);
+        ASSERT_MSG(vma != vm_manager.vma_map.end(), "Invalid memory address");
+        ASSERT_MSG(vma->second.backing_block, "Backing block doesn't exist for address");
+
+        // The returned VMA might be a bigger one encompassing the desired address.
+        auto vma_offset = address - vma->first;
+        ASSERT_MSG(vma_offset + size <= vma->second.size,
+                   "Shared memory exceeds bounds of mapped block");
+
+        shared_memory->backing_block = vma->second.backing_block;
+        shared_memory->backing_block_offset = vma->second.offset + vma_offset;
+    }
 
-    shared_memory->backing_block = vma->second.backing_block;
-    shared_memory->backing_block_offset = vma->second.offset + vma_offset;
     shared_memory->base_address = address;
 
     return shared_memory;