From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59356 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754362AbeBUMqO (ORCPT ); Wed, 21 Feb 2018 07:46:14 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Takashi Iwai Subject: [PATCH 4.4 08/33] ALSA: seq: Fix regression by incorrect ioctl_mutex usages Date: Wed, 21 Feb 2018 13:44:51 +0100 Message-Id: <20180221124410.117039630@linuxfoundation.org> In-Reply-To: <20180221124409.564661689@linuxfoundation.org> References: <20180221124409.564661689@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 This is the revised backport of the upstream commit b3defb791b26ea0683a93a4f49c77ec45ec96f10 We had another backport (e.g. 623e5c8ae32b in 4.4.115), but it applies the new mutex also to the code paths that are invoked via faked kernel-to-kernel ioctls. As reported recently, this leads to a deadlock at suspend (or other scenarios triggering the kernel sequencer client). This patch addresses the issue by taking the mutex only in the code paths invoked by user-space, just like the original fix patch does. Reported-and-tested-by: Andres Bertens Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- Tagged as 4.4.x, but should be applied to other older kernels, too. sound/core/seq/seq_clientmgr.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -2196,7 +2196,6 @@ static int snd_seq_do_ioctl(struct snd_s void __user *arg) { struct seq_ioctl_table *p; - int ret; switch (cmd) { case SNDRV_SEQ_IOCTL_PVERSION: @@ -2210,12 +2209,8 @@ static int snd_seq_do_ioctl(struct snd_s if (! arg) return -EFAULT; for (p = ioctl_tables; p->cmd; p++) { - if (p->cmd == cmd) { - mutex_lock(&client->ioctl_mutex); - ret = p->func(client, arg); - mutex_unlock(&client->ioctl_mutex); - return ret; - } + if (p->cmd == cmd) + return p->func(client, arg); } pr_debug("ALSA: seq unknown ioctl() 0x%x (type='%c', number=0x%02x)\n", cmd, _IOC_TYPE(cmd), _IOC_NR(cmd)); @@ -2226,11 +2221,15 @@ static int snd_seq_do_ioctl(struct snd_s static long snd_seq_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct snd_seq_client *client = file->private_data; + long ret; if (snd_BUG_ON(!client)) return -ENXIO; - return snd_seq_do_ioctl(client, cmd, (void __user *) arg); + mutex_lock(&client->ioctl_mutex); + ret = snd_seq_do_ioctl(client, cmd, (void __user *) arg); + mutex_unlock(&client->ioctl_mutex); + return ret; } #ifdef CONFIG_COMPAT