From 6bed916532295575deaa7e481b1b0c4fe149be38 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Sun, 17 Aug 2025 13:32:37 -0400
Subject: [PATCH 1/3] Check the recursion limit for specialized kwarg calls.

---
 Include/internal/pycore_opcode_metadata.h | 2 +-
 Python/bytecodes.c                        | 1 +
 Python/generated_cases.c.h                | 8 ++++++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
index 7f468bbb932184..bd6b84ec7fd908 100644
--- a/Include/internal/pycore_opcode_metadata.h
+++ b/Include/internal/pycore_opcode_metadata.h
@@ -1354,7 +1354,7 @@ _PyOpcode_macro_expansion[256] = {
     [CALL_ISINSTANCE] = { .nuops = 3, .uops = { { _GUARD_THIRD_NULL, OPARG_SIMPLE, 3 }, { _GUARD_CALLABLE_ISINSTANCE, OPARG_SIMPLE, 3 }, { _CALL_ISINSTANCE, OPARG_SIMPLE, 3 } } },
     [CALL_KW_BOUND_METHOD] = { .nuops = 6, .uops = { { _CHECK_PEP_523, OPARG_SIMPLE, 1 }, { _CHECK_METHOD_VERSION_KW, 2, 1 }, { _EXPAND_METHOD_KW, OPARG_SIMPLE, 3 }, { _PY_FRAME_KW, OPARG_SIMPLE, 3 }, { _SAVE_RETURN_OFFSET, OPARG_SAVE_RETURN_OFFSET, 3 }, { _PUSH_FRAME, OPARG_SIMPLE, 3 } } },
     [CALL_KW_NON_PY] = { .nuops = 3, .uops = { { _CHECK_IS_NOT_PY_CALLABLE_KW, OPARG_SIMPLE, 3 }, { _CALL_KW_NON_PY, OPARG_SIMPLE, 3 }, { _CHECK_PERIODIC_AT_END, OPARG_REPLACED, 3 } } },
-    [CALL_KW_PY] = { .nuops = 5, .uops = { { _CHECK_PEP_523, OPARG_SIMPLE, 1 }, { _CHECK_FUNCTION_VERSION_KW, 2, 1 }, { _PY_FRAME_KW, OPARG_SIMPLE, 3 }, { _SAVE_RETURN_OFFSET, OPARG_SAVE_RETURN_OFFSET, 3 }, { _PUSH_FRAME, OPARG_SIMPLE, 3 } } },
+    [CALL_KW_PY] = { .nuops = 6, .uops = { { _CHECK_PEP_523, OPARG_SIMPLE, 1 }, { _CHECK_FUNCTION_VERSION_KW, 2, 1 }, { _CHECK_RECURSION_REMAINING, OPARG_SIMPLE, 3 }, { _PY_FRAME_KW, OPARG_SIMPLE, 3 }, { _SAVE_RETURN_OFFSET, OPARG_SAVE_RETURN_OFFSET, 3 }, { _PUSH_FRAME, OPARG_SIMPLE, 3 } } },
     [CALL_LEN] = { .nuops = 3, .uops = { { _GUARD_NOS_NULL, OPARG_SIMPLE, 3 }, { _GUARD_CALLABLE_LEN, OPARG_SIMPLE, 3 }, { _CALL_LEN, OPARG_SIMPLE, 3 } } },
     [CALL_LIST_APPEND] = { .nuops = 4, .uops = { { _GUARD_CALLABLE_LIST_APPEND, OPARG_SIMPLE, 3 }, { _GUARD_NOS_NOT_NULL, OPARG_SIMPLE, 3 }, { _GUARD_NOS_LIST, OPARG_SIMPLE, 3 }, { _CALL_LIST_APPEND, OPARG_SIMPLE, 3 } } },
     [CALL_METHOD_DESCRIPTOR_FAST] = { .nuops = 2, .uops = { { _CALL_METHOD_DESCRIPTOR_FAST, OPARG_SIMPLE, 3 }, { _CHECK_PERIODIC_AT_END, OPARG_REPLACED, 3 } } },
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 8a60e48cd465b5..21bae689320eae 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -4721,6 +4721,7 @@ dummy_func(
             unused/1 + // Skip over the counter
             _CHECK_PEP_523 +
             _CHECK_FUNCTION_VERSION_KW +
+            _CHECK_RECURSION_REMAINING +
             _PY_FRAME_KW +
             _SAVE_RETURN_OFFSET +
             _PUSH_FRAME;
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index d63225bb0cd3cd..b6d183a3e63a9c 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -3277,6 +3277,14 @@
                     JUMP_TO_PREDICTED(CALL_KW);
                 }
             }
+            // _CHECK_RECURSION_REMAINING
+            {
+                if (tstate->py_recursion_remaining <= 1) {
+                    UPDATE_MISS_STATS(CALL_KW);
+                    assert(_PyOpcode_Deopt[opcode] == (CALL_KW));
+                    JUMP_TO_PREDICTED(CALL_KW);
+                }
+            }
             // _PY_FRAME_KW
             {
                 kwnames = stack_pointer[-1];

From 8d0f6f02ec16343a2ccb1fc367b7f33bb3599ea5 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Sun, 17 Aug 2025 13:36:17 -0400
Subject: [PATCH 2/3] Add a test.

---
 Lib/test/test_call.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Lib/test/test_call.py b/Lib/test/test_call.py
index 1c73aaafb71fd5..2c28f106ec7cb6 100644
--- a/Lib/test/test_call.py
+++ b/Lib/test/test_call.py
@@ -1074,6 +1074,14 @@ def c_py_recurse(m):
             with self.assertRaises(RecursionError):
                 c_py_recurse(100_000)
 
+    def test_recursion_with_kwargs(self):
+        # GH-137883: The interpreter forgot to check the recursion limit when
+        # calling with keywords.
+        def recurse_kw(a=0):
+            recurse_kw(a=0)
+        with self.assertRaises(RecursionError):
+            recurse_kw()
+
 
 class TestFunctionWithManyArgs(unittest.TestCase):
     def test_function_with_many_args(self):

From ad7c9420a66aa9b6c3e2930b542525a1c34d0f34 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Sun, 17 Aug 2025 13:36:56 -0400
Subject: [PATCH 3/3] Add blurb.

---
 .../2025-08-17-13-36-53.gh-issue-137883.55VDCN.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-08-17-13-36-53.gh-issue-137883.55VDCN.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-08-17-13-36-53.gh-issue-137883.55VDCN.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-08-17-13-36-53.gh-issue-137883.55VDCN.rst
new file mode 100644
index 00000000000000..0bdb2638c86884
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-08-17-13-36-53.gh-issue-137883.55VDCN.rst
@@ -0,0 +1 @@
+Fix runaway recursion when calling a function with keyword arguments.