From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from conuserg-09.nifty.com (conuserg-09.nifty.com [210.131.2.76]) by sourceware.org (Postfix) with ESMTPS id CBA2539484B0 for ; Thu, 13 Jan 2022 12:29:33 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org CBA2539484B0 Authentication-Results: sourceware.org; dmarc=fail (p=none dis=none) header.from=nifty.ne.jp Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=nifty.ne.jp Received: from localhost.localdomain (ae233132.dynamic.ppp.asahi-net.or.jp [14.3.233.132]) (authenticated) by conuserg-09.nifty.com with ESMTP id 20DCSLDA010973; Thu, 13 Jan 2022 21:29:07 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-09.nifty.com 20DCSLDA010973 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.ne.jp; s=dec2015msa; t=1642076947; bh=6lgU7COsWBncTM2ReDRv8VRwn5fFlyQ5CFkcbiBzN6A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UXrzUUpvPGcMi2r+tCE9nGKccvxNIn1418Wwbw3GwYmRyBfIUxXatXcfwN7CenaYY Cm0v62Xz7jbUahx9JGE1bzrm5Vwvhxswpo74cO7nhvpB9YKHRZyR2Y7MC7UmKCB4ao QuAvE++v9rHKJ/OPeVMrj0sdb+SfsAoDm0QKgZcyhNxtVyVjzDZex8MzewnMGOs+Y3 3eBgiKoJFLjxfsYzxVnQqiNHLV+qrw8Mt5IDCxkSalAfh9W8TZ5AeFTTHIPHPRrtFX 5JMWoOZD6YhOzKPk7sYGosGmKK094KUvM1RMWFpk3NMK84EoGm6lTBhBpcAKWf/bxu 7MGclWJscIMTA== X-Nifty-SrcIP: [14.3.233.132] From: Takashi Yano To: cygwin-patches@cygwin.com Subject: [PATCH 4/4] Cygwin: console: Fix potential deadlock regarding acuqiring mutex. Date: Thu, 13 Jan 2022 21:28:11 +0900 Message-Id: <20220113122811.241-5-takashi.yano@nifty.ne.jp> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220113122811.241-1-takashi.yano@nifty.ne.jp> References: <20220113122811.241-1-takashi.yano@nifty.ne.jp> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-10.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin-patches@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Cygwin core component patch submission and discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Jan 2022 12:29:35 -0000 - Acquiring input_mutex and attach_mutex in console code has potential risk of deadlock. This patch fixes the issue. --- winsup/cygwin/fhandler.h | 2 ++ winsup/cygwin/select.cc | 7 ++++--- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h index 0cea1b7f3..fb4747608 100644 --- a/winsup/cygwin/fhandler.h +++ b/winsup/cygwin/fhandler.h @@ -2208,9 +2208,11 @@ private: void acquire_input_mutex_if_necessary (DWORD ms) { acquire_input_mutex (ms); + acquire_attach_mutex (ms); } void release_input_mutex_if_necessary (void) { + release_attach_mutex (); release_input_mutex (); } diff --git a/winsup/cygwin/select.cc b/winsup/cygwin/select.cc index 5b8fc0f81..d01a319ef 100644 --- a/winsup/cygwin/select.cc +++ b/winsup/cygwin/select.cc @@ -1122,29 +1122,30 @@ peek_console (select_record *me, bool) HANDLE h; set_handle_or_return_if_not_open (h, me); + fh->acquire_input_mutex (mutex_timeout); acquire_attach_mutex (mutex_timeout); while (!fh->input_ready && !fh->get_cons_readahead_valid ()) { if (fh->bg_check (SIGTTIN, true) <= bg_eof) { release_attach_mutex (); + fh->release_input_mutex (); return me->read_ready = true; } else if (!PeekConsoleInputW (h, &irec, 1, &events_read) || !events_read) break; - fh->acquire_input_mutex (mutex_timeout); if (fhandler_console::input_winch == fh->process_input_message () && global_sigs[SIGWINCH].sa_handler != SIG_IGN && global_sigs[SIGWINCH].sa_handler != SIG_DFL) { set_sig_errno (EINTR); - fh->release_input_mutex (); release_attach_mutex (); + fh->release_input_mutex (); return -1; } - fh->release_input_mutex (); } release_attach_mutex (); + fh->release_input_mutex (); if (fh->input_ready || fh->get_cons_readahead_valid ()) return me->read_ready = true; -- 2.34.1