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ALSA: seq: Don't handle loop timeout at snd_seq_pool_done()

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commit 37a7ea4a9b 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@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>
This commit is contained in:
Takashi Iwai
2017-02-06 15:09:48 +01:00
committed by Greg Kroah-Hartman
parent 5024b2fb8e
commit 23b1595b97
1 changed files with 1 additions and 8 deletions
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9
sound/core/seq/seq_memory.c
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@@ -419,7 +419,6 @@ int snd_seq_pool_done(struct snd_seq_pool *pool)
{ {
unsigned long flags; unsigned long flags;
struct snd_seq_event_cell *ptr; struct snd_seq_event_cell *ptr;
int max_count = 5 * HZ;
if (snd_BUG_ON(!pool)) if (snd_BUG_ON(!pool))
return -EINVAL; return -EINVAL;
@@ -432,14 +431,8 @@ int snd_seq_pool_done(struct snd_seq_pool *pool)
if (waitqueue_active(&pool->output_sleep)) if (waitqueue_active(&pool->output_sleep))
wake_up(&pool->output_sleep); wake_up(&pool->output_sleep);
while (atomic_read(&pool->counter) > 0) { 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;
}
schedule_timeout_uninterruptible(1); schedule_timeout_uninterruptible(1);
max_count--;
}
/* release all resources */ /* release all resources */
spin_lock_irqsave(&pool->lock, flags); spin_lock_irqsave(&pool->lock, flags);