From 38ca12467c0105060d60e4106193cc74e9506bd9 Mon Sep 17 00:00:00 2001
From: Abdul Mohammad <154353563+abdulm5@users.noreply.github.com>
Date: Sat, 15 Aug 2026 23:12:24 -0400
Subject: [PATCH] gh-155504: Set the interpreter before fallible thread state
 initialization (GH-155590) (cherry picked from commit
 94a75f74a13a11b4025c02612c47f61dec0a7398)

Co-authored-by: Abdul Mohammad <154353563+abdulm5@users.noreply.github.com>
---
 .../2026-08-11-13-50-35.gh-issue-155504.PsTqZm.rst              | 2 ++
 Python/pystate.c                                                | 2 ++
 2 files changed, 4 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-13-50-35.gh-issue-155504.PsTqZm.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-13-50-35.gh-issue-155504.PsTqZm.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-13-50-35.gh-issue-155504.PsTqZm.rst
new file mode 100644
index 00000000000000..e042bf3554e6f0
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-08-11-13-50-35.gh-issue-155504.PsTqZm.rst
@@ -0,0 +1,2 @@
+Fix a crash when thread state creation fails before the thread state is fully
+initialized.
diff --git a/Python/pystate.c b/Python/pystate.c
index d1505be4acf50f..5de6defb4bdc3e 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -1506,6 +1506,8 @@ alloc_threadstate(PyInterpreterState *interp)
         }
         reset_threadstate(tstate);
     }
+    // Set the interpreter before any later initialization can fail.
+    tstate->base.interp = interp;
     return tstate;
 }