This is a note to let you know that I've just added the patch titled
ALSA: seq: Fix regression by incorrect ioctl_mutex usages
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: alsa-seq-fix-regression-by-incorrect-ioctl_mutex-usages.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From tiwai@suse.de Mon Feb 19 17:39:59 2018
From: Takashi Iwai tiwai@suse.de Date: Mon, 19 Feb 2018 17:16:01 +0100 Subject: ALSA: seq: Fix regression by incorrect ioctl_mutex usages To: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Andres Bertens abertensu@yahoo.com, ben@decadent.org.uk, stable@vger.kernel.org Message-ID: 20180219161601.24110-1-tiwai@suse.de
From: Takashi Iwai tiwai@suse.de
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 abertensu@yahoo.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org ---
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
Patches currently in stable-queue which might be from tiwai@suse.de are
queue-4.4/alsa-seq-fix-regression-by-incorrect-ioctl_mutex-usages.patch