From c723076373dac50287fba6ccd1067301b67dbfa4 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 6 Feb 2017 15:09:48 +0100 Subject: [PATCH] ALSA: seq: Don't handle loop timeout at snd_seq_pool_done() 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@mail.gmail.com Reported-by: Dmitry Vyukov Signed-off-by: Takashi Iwai [bwh: Backported to 3.2: deleted log statement is slightly different] Signed-off-by: Ben Hutchings --- sound/core/seq/seq_memory.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/sound/core/seq/seq_memory.c b/sound/core/seq/seq_memory.c index e0e683cd3926..9f20d3c24d76 100644 --- a/sound/core/seq/seq_memory.c +++ b/sound/core/seq/seq_memory.c @@ -421,7 +421,6 @@ int snd_seq_pool_done(struct snd_seq_pool *pool) { unsigned long flags; struct snd_seq_event_cell *ptr; - int max_count = 5 * HZ; if (snd_BUG_ON(!pool)) return -EINVAL; @@ -434,14 +433,8 @@ int snd_seq_pool_done(struct snd_seq_pool *pool) if (waitqueue_active(&pool->output_sleep)) wake_up(&pool->output_sleep); - while (atomic_read(&pool->counter) > 0) { - if (max_count == 0) { - snd_printk(KERN_WARNING "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); -- 2.39.2