This is a note to let you know that I've just added the patch titled
ALSA: seq: Don't handle loop timeout at snd_seq_pool_done()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-seq-don-t-handle-loop-timeout-at-snd_seq_pool_done.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@xxxxxxxxxxxxxxx> know about it.
>From 37a7ea4a9b81f6a864c10a7cb0b96458df5310a3 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Mon, 6 Feb 2017 15:09:48 +0100
Subject: ALSA: seq: Don't handle loop timeout at snd_seq_pool_done()
From: Takashi Iwai <tiwai@xxxxxxx>
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@xxxxxxxxxxxxxx
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-4.4/alsa-seq-don-t-handle-loop-timeout-at-snd_seq_pool_done.patch
queue-4.4/alsa-seq-fix-race-at-creating-a-queue.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html