Backport coredump buffer ownership fixes to CUDA 12

Carry forward #2399: retain borrowed setter bytes and release getter-owned storage. Keep this runtime maintenance separate from the build integration.

Signed-off-by: Ralf W. Grosse-Kunstleve <rgrossekunst@nvidia.com>

Author: rwgk

cuda_bindings_12/cuda/bindings/_lib/utils.pxd

@@ -152,6 +152,7 @@ cdef class _HelperCUcoredumpSettings:
     cdef cydriver.CUcoredumpSettings_enum _attrib
     cdef bint _is_getter
     cdef size_t _size
+    cdef object _references  # keeps caller bytes alive so _charstar stays valid
 
     # Return values
     cdef cpp_bool _bool

cuda_bindings_12/cuda/bindings/_lib/utils.pxi

@@ -734,6 +734,8 @@ cdef class _HelperCUcoredumpSettings:
                 self._cptr = <void*><void_ptr>self._charstar
                 self._size = 1024
             else:
+                # Keep a reference so the borrowed _charstar buffer stays alive.
+                self._references = init_value
                 self._charstar = init_value
                 self._cptr = <void*><void_ptr>self._charstar
                 self._size = len(init_value)
@@ -756,7 +758,9 @@ cdef class _HelperCUcoredumpSettings:
             raise TypeError('Unsupported attribute: {}'.format(attr.name))
 
     def __dealloc__(self):
-        pass
+        # Only the getter owns heap storage; the setter borrows caller bytes.
+        if self._is_getter:
+            free(self._charstar)
 
     @property
     def cptr(self):