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null-terminate registry value in windows_get_device_registry_entry #1948

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Merged
charles-lunarg merged 1 commit into from
Jun 24, 2026
+8 −1
Merged

null-terminate registry value in windows_get_device_registry_entry #1948

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9 changes: 8 additions & 1 deletion loader/loader_windows.c
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Original file line number Diff line number Diff line change
Expand Up @@ -171,7 +171,9 @@ VkResult windows_get_device_registry_entry(const struct loader_instance *inst, s
goto out;
}

manifest_path = loader_instance_heap_alloc(inst, requiredSize, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
// Registry string values are not guaranteed to be stored with a terminating null (see RegQueryValueEx). Reserve two
// extra bytes so the value can be terminated after it is read, before it is walked with strlen below.
manifest_path = loader_instance_heap_alloc(inst, requiredSize + 2, VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE);
if (manifest_path == NULL) {
loader_log(inst, VULKAN_LOADER_ERROR_BIT | VULKAN_LOADER_DRIVER_BIT, 0,
"windows_get_device_registry_entry: Failed to allocate space for DriverName.");
Expand All @@ -195,6 +197,11 @@ VkResult windows_get_device_registry_entry(const struct loader_instance *inst, s
goto out;
}

// requiredSize now holds the number of bytes RegQueryValueEx wrote, which is at most the size queried for the
// allocation, so the two terminators always fit. This keeps the strlen walk in windows_add_json_entry in bounds.
manifest_path[requiredSize] = '\0';
manifest_path[requiredSize + 1] = '\0';

res = windows_add_json_entry(inst, search_paths, value_name, data_type, manifest_path, requiredSize);

out:
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