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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 15:31:55 -0800
commite21cf1926a2f3794db8cdec33153e1b5d92d6598 (patch)
tree28b6d63999182cc998bb46ee9be2dc798c27b171
parent3d0c02d2c0fa9fbdea2da035b57ff3c6a96a2bb8 (diff)
downloadlinux-linaro-stable-e21cf1926a2f3794db8cdec33153e1b5d92d6598.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