linux-kernel - Re: next-0519 on thinkpad x60: sound related? window manager crash

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Message-ID: <s5hr1uogtna.wl-tiwai@suse.de>
Date:   Tue, 09 Jun 2020 17:12:41 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     "Alex Xu (Hello71)" <alex_y_xu@...oo.ca>
Cc:     Christoph Hellwig <hch@....de>, <alsa-devel@...a-project.org>,
        <bp@...en8.de>, <hch@...radead.org>, <hpa@...or.com>,
        <linux-kernel@...r.kernel.org>, <mingo@...hat.com>,
        Pavel Machek <pavel@....cz>, <perex@...ex.cz>,
        <rientjes@...gle.com>, <tglx@...utronix.de>, <tiwai@...e.com>,
        <x86@...nel.org>
Subject: Re: next-0519 on thinkpad x60: sound related? window manager crash

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);