From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 7868) id 448DF3835C07; Fri, 14 Jan 2022 14:15:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 448DF3835C07 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Takashi Yano To: cygwin-cvs@sourceware.org Subject: [newlib-cygwin/cygwin-3_3-branch] Cygwin: console: Fix potential deadlock regarding acuqiring mutex. X-Act-Checkin: newlib-cygwin X-Git-Author: Takashi Yano X-Git-Refname: refs/heads/cygwin-3_3-branch X-Git-Oldrev: 335fa943c7d3ffeaa7b2ffb185b18476b23fc459 X-Git-Newrev: 441ca95fef3516d70b2a8339f72b645e76683174 Message-Id: <20220114141532.448DF3835C07@sourceware.org> Date: Fri, 14 Jan 2022 14:15:32 +0000 (GMT) X-BeenThere: cygwin-cvs@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Cygwin core component git logs List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Jan 2022 14:15:32 -0000 https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=441ca95fef3516d70b2a8339f72b645e76683174 commit 441ca95fef3516d70b2a8339f72b645e76683174 Author: Takashi Yano Date: Thu Jan 13 20:57:15 2022 +0900 Cygwin: console: Fix potential deadlock regarding acuqiring mutex. - Acquiring input_mutex and attach_mutex in console code has potential risk of deadlock. This patch fixes the issue. Diff: --- 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 630293ff8..4226bfd69 100644 --- a/winsup/cygwin/fhandler.h +++ b/winsup/cygwin/fhandler.h @@ -2209,9 +2209,11 @@ 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;