kstd: fix shared_ptr constructor race

1 files changed, 11 insertions, 4 deletions

diff --git a/libs/kstd/kstd/bits/shared_ptr.hpp b/libs/kstd/kstd/bits/shared_ptr.hpp
index ce4bfb7f..f4aed34e 100644
--- a/libs/kstd/kstd/bits/shared_ptr.hpp
+++ b/libs/kstd/kstd/bits/shared_ptr.hpp
@@ -266,11 +266,18 @@ namespace kstd
         : pointer(nullptr)
         , control(nullptr)
     {
-      if (other.control != nullptr && other.control->shared_count != 0)
+      if (other.control)
       {
-        pointer = other.pointer;
-        control = other.control;
-        ++(control->shared_count);
+        auto count = other.control->shared_count.load(std::memory_order::relaxed);
+        while (count != 0 && !other.control->shared_count.compare_exchange_weak(
+                                 count, count + 1, std::memory_order::acquire, std::memory_order::relaxed))
+          ;
+
+        if (count != 0)
+        {
+          pointer = other.pointer;
+          control = other.control;
+        }
       }
     }