From: Hood Chatham <roberthoodchatham@gmail.com>
Date: Sat, 19 Jul 2025 19:43:50 +0000 (+0200)
Subject: gh-124621: Emscripten: Fix regression in use-after-close error handling (#136837)
X-Git-Tag: v3.15.0a1~928
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=800d37feca2e0ea3343995b3b817b653db2f9034;p=thirdparty%2FPython%2Fcpython.git

gh-124621: Emscripten: Fix regression in use-after-close error handling (#136837)
---

diff --git a/Python/emscripten_syscalls.c b/Python/emscripten_syscalls.c
index bd5cc07071f2..886262acbc68 100644
--- a/Python/emscripten_syscalls.c
+++ b/Python/emscripten_syscalls.c
@@ -148,10 +148,17 @@ EM_JS_MACROS(__externref_t, __maybe_fd_read_async, (
     size_t iovcnt,
     __wasi_size_t *nread
 ), {
-    var stream = SYSCALLS.getStreamFromFD(fd);
     if (!WebAssembly.promising) {
         return null;
     }
+    var stream;
+    try {
+        stream = SYSCALLS.getStreamFromFD(fd);
+    } catch (e) {
+        // If the fd was already closed or never existed, getStreamFromFD()
+        // raises. We'll let fd_read_orig() handle setting errno.
+        return null;
+    }
     if (!stream.stream_ops.readAsync) {
         // Not an async device. Fall back to __wasi_fd_read_orig().
         return null;