From 392a2cba66be7a4b7ba9b8c60a06ba4a7b48d2b2 Mon Sep 17 00:00:00 2001
From: Johannes Schlatow <johannes.schlatow@genode-labs.com>
Date: Thu, 10 Feb 2022 13:47:14 +0100
Subject: [PATCH] libc: fix page fault in socket_fs_plugin

In the error case of socket_fs_accept() the Unconfirmed utility was
incompletely applied with the result of executing the cleanup routines
in the wrong order.

Fixes #4417
---
 .../src/lib/libc/internal/unconfirmed.h       | 41 -------------------
 .../libports/src/lib/libc/socket_fs_plugin.cc |  5 +--
 2 files changed, 1 insertion(+), 45 deletions(-)
 delete mode 100644 repos/libports/src/lib/libc/internal/unconfirmed.h

diff --git a/repos/libports/src/lib/libc/internal/unconfirmed.h b/repos/libports/src/lib/libc/internal/unconfirmed.h
deleted file mode 100644
index 280264f388..0000000000
--- a/repos/libports/src/lib/libc/internal/unconfirmed.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * \brief  Utility to automatically unroll unconfirmed operations
- * \author Christian Helmuth
- * \date   2020-07-31
- */
-
-/*
- * Copyright (C) 2020 Genode Labs GmbH
- *
- * This file is part of the Genode OS framework, which is distributed
- * under the terms of the GNU Affero General Public License version 3.
- */
-
-#ifndef _LIBC__INTERNAL__UNCONFIRMED_H_
-#define _LIBC__INTERNAL__UNCONFIRMED_H_
-
-namespace Libc {
-	template <typename> struct Unconfirmed;
-
-	template <typename FUNC>
-	Unconfirmed<FUNC> make_unconfirmed(FUNC const &cleanup)
-	{
-		return { cleanup };
-	}
-};
-
-
-template <typename FUNC>
-struct Libc::Unconfirmed
-{
-	bool confirmed { false };
-
-	FUNC const &cleanup;
-
-	Unconfirmed(FUNC const &cleanup) : cleanup(cleanup) { }
-	~Unconfirmed() { if (!confirmed) cleanup(); }
-
-	void confirm() { confirmed = true; }
-};
-
-#endif /* _LIBC__INTERNAL__UNCONFIRMED_H_ */
diff --git a/repos/libports/src/lib/libc/socket_fs_plugin.cc b/repos/libports/src/lib/libc/socket_fs_plugin.cc
index d011ea3b84..7295ab3be7 100644
--- a/repos/libports/src/lib/libc/socket_fs_plugin.cc
+++ b/repos/libports/src/lib/libc/socket_fs_plugin.cc
@@ -43,7 +43,6 @@
 #include <internal/init.h>
 #include <internal/suspend.h>
 #include <internal/pthread.h>
-#include <internal/unconfirmed.h>
 
 
 namespace Libc {
@@ -604,12 +603,11 @@ extern "C" int socket_fs_accept(int libc_fd, sockaddr *addr, socklen_t *addrlen)
 		return Errno(EMFILE);
 	}
 
-	auto _accept_fd = make_unconfirmed([&] { file_descriptor_allocator()->free(accept_fd); });
-
 	if (addr && addrlen) {
 		Socket_fs::Remote_functor func(*accept_context, false);
 		int ret = read_sockaddr_in(func, (sockaddr_in *)addr, addrlen);
 		if (ret == -1) {
+			file_descriptor_allocator()->free(accept_fd);
 			Libc::Allocator alloc { };
 			destroy(alloc, accept_context);
 			return ret;
@@ -619,7 +617,6 @@ extern "C" int socket_fs_accept(int libc_fd, sockaddr *addr, socklen_t *addrlen)
 	/* inherit the O_NONBLOCK flag if set */
 	accept_context->fd_flags(listen_context->fd_flags());
 
-	_accept_fd.confirm();
 	return accept_fd->libc_fd;
 }