From patchwork Wed Aug 28 12:29:11 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 270490 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id BEB852C009F for ; Wed, 28 Aug 2013 22:31:41 +1000 (EST) Received: from localhost ([::1]:34395 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VEeuR-0006Wg-RF for incoming@patchwork.ozlabs.org; Wed, 28 Aug 2013 08:31:39 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52104) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VEesM-0003wM-Sk for qemu-devel@nongnu.org; Wed, 28 Aug 2013 08:29:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VEesH-0007b4-SB for qemu-devel@nongnu.org; Wed, 28 Aug 2013 08:29:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6766) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VEesH-0007ay-Iw; Wed, 28 Aug 2013 08:29:25 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7SCTO6n010844 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 28 Aug 2013 08:29:24 -0400 Received: from localhost (dhcp193-119.pnq.redhat.com [10.65.193.119]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r7SCTMlg000663; Wed, 28 Aug 2013 08:29:23 -0400 From: Amit Shah To: qemu list Date: Wed, 28 Aug 2013 17:59:11 +0530 Message-Id: In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: qemu-stable@nongnu.org, Hans de Goede , Gerd Hoffmann , Anthony Liguori , Amit Shah , Paolo Bonzini Subject: [Qemu-devel] [PATCH v2 3/3] char: remove watch callback on chardev detach from frontend X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org If a frontend device releases the chardev (via unplug), the chr handlers are set to NULL via qdev's exit callbacks invoking qemu_chr_add_handlers(). If the chardev had a pending operation, a callback will be invoked, which will try to access data in the just-released frontend, causing a segfault. Ensure the callbacks are disabled when frontends release chardevs. This was seen when a virtio-serial port was unplugged when heavy guest->host IO was in progress (causing a callback to be registered). In the window in which the throttling was active, unplugging ports caused a qemu segfault. https://bugzilla.redhat.com/show_bug.cgi?id=985205 CC: Reported-by: Sibiao Luo Signed-off-by: Amit Shah --- qemu-char.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/qemu-char.c b/qemu-char.c index 44d993a..0cba7d4 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -193,6 +193,8 @@ void qemu_chr_fe_printf(CharDriverState *s, const char *fmt, ...) va_end(ap); } +static void remove_fd_in_watch(CharDriverState *chr); + void qemu_chr_add_handlers(CharDriverState *s, IOCanReadHandler *fd_can_read, IOReadHandler *fd_read, @@ -203,6 +205,7 @@ void qemu_chr_add_handlers(CharDriverState *s, if (!opaque && !fd_can_read && !fd_read && !fd_event) { fe_open = 0; + remove_fd_in_watch(s); } else { fe_open = 1; }