From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932231AbcBWVyS (ORCPT ); Tue, 23 Feb 2016 16:54:18 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41713 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755597AbcBWVo6 (ORCPT ); Tue, 23 Feb 2016 16:44:58 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Takashi Iwai" , "Dmitry Vyukov" Date: Tue, 23 Feb 2016 21:42:03 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 31/67] ALSA: seq: Fix race at closing in virmidi driver In-Reply-To: X-SA-Exim-Connect-IP: 92.40.248.141 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 2d1b5c08366acd46c35a2e9aba5d650cb5bf5c19 upstream. The virmidi driver has an open race at closing its assigned rawmidi device, and this may lead to use-after-free in snd_seq_deliver_single_event(). Plug the hole by properly protecting the linked list deletion and calling in the right order in snd_virmidi_input_close(). BugLink: http://lkml.kernel.org/r/CACT4Y+Zd66+w12fNN85-425cVQT=K23kWbhnCEcMB8s3us-Frw@mail.gmail.com Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/core/seq/seq_virmidi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/sound/core/seq/seq_virmidi.c +++ b/sound/core/seq/seq_virmidi.c @@ -254,9 +254,13 @@ static int snd_virmidi_output_open(struc */ static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream) { + struct snd_virmidi_dev *rdev = substream->rmidi->private_data; struct snd_virmidi *vmidi = substream->runtime->private_data; - snd_midi_event_free(vmidi->parser); + + write_lock_irq(&rdev->filelist_lock); list_del(&vmidi->list); + write_unlock_irq(&rdev->filelist_lock); + snd_midi_event_free(vmidi->parser); substream->runtime->private_data = NULL; kfree(vmidi); return 0;