From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30E7FC432C0 for ; Wed, 20 Nov 2019 15:43:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D29420714 for ; Wed, 20 Nov 2019 15:43:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732241AbfKTPnG (ORCPT ); Wed, 20 Nov 2019 10:43:06 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52808 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731318AbfKTPkT (ORCPT ); Wed, 20 Nov 2019 10:40:19 -0500 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iXS5V-0004b8-1K; Wed, 20 Nov 2019 15:40:13 +0000 Received: from ben by deadeye with local (Exim 4.93-RC1) (envelope-from ) id 1iXS5U-0004JI-9O; Wed, 20 Nov 2019 15:40:12 +0000 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, Denis Kirjanov , "Takashi Iwai" , syzbot+4a75454b9ca2777f35c7@syzkaller.appspotmail.com Date: Wed, 20 Nov 2019 15:37:58 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 48/83] ALSA: seq: Fix potential concurrent access to the deleted pool In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 75545304eba6a3d282f923b96a466dc25a81e359 upstream. The input pool of a client might be deleted via the resize ioctl, the the access to it should be covered by the proper locks. Currently the only missing place is the call in snd_seq_ioctl_get_client_pool(), and this patch papers over it. Reported-by: syzbot+4a75454b9ca2777f35c7@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- sound/core/seq/seq_clientmgr.c | 3 +-- sound/core/seq/seq_fifo.c | 17 +++++++++++++++++ sound/core/seq/seq_fifo.h | 2 ++ 3 files changed, 20 insertions(+), 2 deletions(-) --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -1911,8 +1911,7 @@ static int snd_seq_ioctl_get_client_pool if (cptr->type == USER_CLIENT) { info.input_pool = cptr->data.user.fifo_pool_size; info.input_free = info.input_pool; - if (cptr->data.user.fifo) - info.input_free = snd_seq_unused_cells(cptr->data.user.fifo->pool); + info.input_free = snd_seq_fifo_unused_cells(cptr->data.user.fifo); } else { info.input_pool = 0; info.input_free = 0; --- a/sound/core/seq/seq_fifo.c +++ b/sound/core/seq/seq_fifo.c @@ -278,3 +278,20 @@ int snd_seq_fifo_resize(struct snd_seq_f return 0; } + +/* get the number of unused cells safely */ +int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f) +{ + unsigned long flags; + int cells; + + if (!f) + return 0; + + snd_use_lock_use(&f->use_lock); + spin_lock_irqsave(&f->lock, flags); + cells = snd_seq_unused_cells(f->pool); + spin_unlock_irqrestore(&f->lock, flags); + snd_use_lock_free(&f->use_lock); + return cells; +} --- a/sound/core/seq/seq_fifo.h +++ b/sound/core/seq/seq_fifo.h @@ -68,5 +68,7 @@ int snd_seq_fifo_poll_wait(struct snd_se /* resize pool in fifo */ int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize); +/* get the number of unused cells safely */ +int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f); #endif