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authorTakashi Iwai <tiwai@suse.de>2016-03-01 18:30:18 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-03-09 15:33:27 -0800
commit388cfb51f24f440e88d9fd80b29c0ee3457ef5bc (patch)
treec1b1122eb4e4cb123d5b63c86beb92e1a5de6bc9
parent2f4ad23ad58f502b1b4f2cd6546ea57248e048c8 (diff)
downloadlinux-linaro-stable-388cfb51f24f440e88d9fd80b29c0ee3457ef5bc.tar.gz
ALSA: seq: oss: Don't drain at closing a client
commit 197b958c1e76a575d77038cc98b4bebc2134279f upstream. The OSS sequencer client tries to drain the pending events at releasing. Unfortunately, as spotted by syzkaller fuzzer, this may lead to an unkillable process state when the event has been queued at the far future. Since the process being released can't be signaled any longer, it remains and waits for the echo-back event in that far future. Back to history, the draining feature was implemented at the time we misinterpreted POSIX definition for blocking file operation. Actually, such a behavior is superfluous at release, and we should just release the device as is instead of keeping it up forever. This patch just removes the draining call that may block the release for too long time unexpectedly. BugLink: http://lkml.kernel.org/r/CACT4Y+Y4kD-aBGj37rf-xBw9bH3GMU6P+MYg4W1e-s-paVD2pg@mail.gmail.com Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--sound/core/seq/oss/seq_oss.c2
-rw-r--r--sound/core/seq/oss/seq_oss_device.h1
-rw-r--r--sound/core/seq/oss/seq_oss_init.c17
3 files changed, 0 insertions, 20 deletions
diff --git a/sound/core/seq/oss/seq_oss.c b/sound/core/seq/oss/seq_oss.c
index 8d4d5e853efe..ab774954c985 100644
--- a/sound/core/seq/oss/seq_oss.c
+++ b/sound/core/seq/oss/seq_oss.c
@@ -150,8 +150,6 @@ odev_release(struct inode *inode, struct file *file)
if ((dp = file->private_data) == NULL)
return 0;
- snd_seq_oss_drain_write(dp);
-
mutex_lock(&register_mutex);
snd_seq_oss_release(dp);
mutex_unlock(&register_mutex);
diff --git a/sound/core/seq/oss/seq_oss_device.h b/sound/core/seq/oss/seq_oss_device.h
index c0154a959d55..2464112b08ad 100644
--- a/sound/core/seq/oss/seq_oss_device.h
+++ b/sound/core/seq/oss/seq_oss_device.h
@@ -131,7 +131,6 @@ int snd_seq_oss_write(struct seq_oss_devinfo *dp, const char __user *buf, int co
unsigned int snd_seq_oss_poll(struct seq_oss_devinfo *dp, struct file *file, poll_table * wait);
void snd_seq_oss_reset(struct seq_oss_devinfo *dp);
-void snd_seq_oss_drain_write(struct seq_oss_devinfo *dp);
/* */
void snd_seq_oss_process_queue(struct seq_oss_devinfo *dp, abstime_t time);
diff --git a/sound/core/seq/oss/seq_oss_init.c b/sound/core/seq/oss/seq_oss_init.c
index b3f39b5ed742..f9e09e458227 100644
--- a/sound/core/seq/oss/seq_oss_init.c
+++ b/sound/core/seq/oss/seq_oss_init.c
@@ -457,23 +457,6 @@ snd_seq_oss_release(struct seq_oss_devinfo *dp)
/*
- * Wait until the queue is empty (if we don't have nonblock)
- */
-void
-snd_seq_oss_drain_write(struct seq_oss_devinfo *dp)
-{
- if (! dp->timer->running)
- return;
- if (is_write_mode(dp->file_mode) && !is_nonblock_mode(dp->file_mode) &&
- dp->writeq) {
- debug_printk(("syncing..\n"));
- while (snd_seq_oss_writeq_sync(dp->writeq))
- ;
- }
-}
-
-
-/*
* reset sequencer devices
*/
void