From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:43120 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753404AbdBMNF3 (ORCPT ); Mon, 13 Feb 2017 08:05:29 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dmitry Vyukov , Takashi Iwai Subject: [PATCH 4.4 19/20] ALSA: seq: Dont handle loop timeout at snd_seq_pool_done() Date: Mon, 13 Feb 2017 05:05:04 -0800 Message-Id: <20170213130404.370495606@linuxfoundation.org> In-Reply-To: <20170213130403.531813333@linuxfoundation.org> References: <20170213130403.531813333@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 37a7ea4a9b81f6a864c10a7cb0b96458df5310a3 upstream. snd_seq_pool_done() syncs with closing of all opened threads, but it aborts the wait loop with a timeout, and proceeds to the release resource even if not all threads have been closed. The timeout was 5 seconds, and if you run a crazy stuff, it can exceed easily, and may result in the access of the invalid memory address -- this is what syzkaller detected in a bug report. As a fix, let the code graduate from naiveness, simply remove the loop timeout. BugLink: http://lkml.kernel.org/r/CACT4Y+YdhDV2H5LLzDTJDVF-qiYHUHhtRaW4rbb4gUhTCQB81w@mail.gmail.com Reported-by: Dmitry Vyukov Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/seq/seq_memory.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) --- a/sound/core/seq/seq_memory.c +++ b/sound/core/seq/seq_memory.c @@ -419,7 +419,6 @@ int snd_seq_pool_done(struct snd_seq_poo { unsigned long flags; struct snd_seq_event_cell *ptr; - int max_count = 5 * HZ; if (snd_BUG_ON(!pool)) return -EINVAL; @@ -432,14 +431,8 @@ int snd_seq_pool_done(struct snd_seq_poo if (waitqueue_active(&pool->output_sleep)) wake_up(&pool->output_sleep); - while (atomic_read(&pool->counter) > 0) { - if (max_count == 0) { - pr_warn("ALSA: snd_seq_pool_done timeout: %d cells remain\n", atomic_read(&pool->counter)); - break; - } + while (atomic_read(&pool->counter) > 0) schedule_timeout_uninterruptible(1); - max_count--; - } /* release all resources */ spin_lock_irqsave(&pool->lock, flags);