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Date:   Tue, 09 Jun 2020 17:12:41 +0200
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From:   Takashi Iwai <tiwai@suse.de>
To:     "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc:     Christoph Hellwig <hch@lst.de>, <alsa-devel@alsa-project.org>,
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        Pavel Machek <pavel@ucw.cz>, <perex@perex.cz>,
        <rientjes@google.com>, <tglx@linutronix.de>, <tiwai@suse.com>,
        <x86@kernel.org>
Subject: Re: next-0519 on thinkpad x60: sound related? window manager crash
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On Tue, 09 Jun 2020 13:47:33 +0200,
Christoph Hellwig wrote:
> 
> Alex, can you try this patch?

Also could you check whether just papering over the memset() call
alone avoids the crash like below?  For PulseAudio and dmix/dsnoop,
it's the only code path that accesses the vmapped buffer, I believe.

If this works more or less, I'll cook a more comprehensive fix.


thanks,

Takashi

--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -754,9 +754,11 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
 	while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
 		runtime->boundary *= 2;
 
+#if 0
 	/* clear the buffer for avoiding possible kernel info leaks */
 	if (runtime->dma_area && !substream->ops->copy_user)
 		memset(runtime->dma_area, 0, runtime->dma_bytes);
+#endif
 
 	snd_pcm_timer_resolution_change(substream);
 	snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);