From d23dc631eee68e90444dfabba89a8ee86304ebe8 Mon Sep 17 00:00:00 2001
From: youknowdot <dot@youknowone.org>
Date: Sat, 10 Oct 2026 10:55:52 -0700
Subject: [PATCH] Validate lock timeout range before acquire restrictions
 (#9061)

Preserve CPython signed nanosecond conversion precedence for reentrant and nonblocking acquisition, without changing the platform timeout maximum.

Assisted-by: OpenAI Codex:model identifier unavailable
---
 crates/vm/src/stdlib/_thread.rs        |  5 +++++
 extra_tests/snippets/builtin_thread.py | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/crates/vm/src/stdlib/_thread.rs b/crates/vm/src/stdlib/_thread.rs
index efe4ed302..a2bab628a 100644
--- a/crates/vm/src/stdlib/_thread.rs
+++ b/crates/vm/src/stdlib/_thread.rs
@@ -106,6 +106,11 @@ pub(crate) mod _thread {
 
     fn validate_acquire_args(args: AcquireArgs, vm: &VirtualMachine) -> PyResult<(bool, f64)> {
         let timeout = args.timeout.to_secs_f64();
+        // CPython checks the signed nanosecond range before acquire-specific restrictions.
+        let timeout_ns = timeout * 1_000_000_000.0;
+        if !(i64::MIN as f64..-(i64::MIN as f64)).contains(&timeout_ns) {
+            return Err(vm.new_overflow_error("timestamp out of range for C PyTime_t"));
+        }
         if !args.blocking && timeout != -1.0 {
             return Err(vm.new_value_error("can't specify a timeout for a non-blocking call"));
         }
diff --git a/extra_tests/snippets/builtin_thread.py b/extra_tests/snippets/builtin_thread.py
index 3d12e76cc..b98a2a42e 100644
--- a/extra_tests/snippets/builtin_thread.py
+++ b/extra_tests/snippets/builtin_thread.py
@@ -9,6 +9,16 @@ for error, kwargs in (
     (ValueError, {"blocking": False, "timeout": 1}),
     (ValueError, {"timeout": -2}),
     (OverflowError, {"timeout": _thread.TIMEOUT_MAX + 1}),
+    (OverflowError, {"blocking": False, "timeout": 2**63 / 1e9}),
+    (OverflowError, {"blocking": False, "timeout": -9_223_372_037}),
+    (OverflowError, {"timeout": -9_223_372_037}),
+    (OverflowError, {"blocking": False, "timeout": float("inf")}),
+    (OverflowError, {"timeout": float("inf")}),
+    (OverflowError, {"blocking": False, "timeout": float("-inf")}),
+    (OverflowError, {"timeout": float("-inf")}),
+    (ValueError, {"timeout": -(2**63) / 1e9}),
+    (ValueError, {"blocking": False, "timeout": 4_294_968}),
+    (ValueError, {"timeout": -4_294_968}),
 ):
     lock = _thread.RLock()
     assert lock.acquire()