linux-kernel - [PATCH 3.2 024/126] ALSA: ali5451: Fix out-of-bound position reporting

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Message-ID: <lsq.1487198494.443589254@decadent.org.uk>
Date:   Wed, 15 Feb 2017 22:41:34 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Takashi Iwai" <tiwai@...e.de>,
        "Enrico Mioso" <mrkiko.rs@...il.com>
Subject: [PATCH 3.2 024/126] ALSA: ali5451: Fix out-of-bound position
 reporting

3.2.85-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@...e.de>

commit db68577966abc1aeae4ec597b3dcfa0d56e92041 upstream.

The pointer callbacks of ali5451 driver may return the value at the
boundary occasionally, and it results in the kernel warning like
  snd_ali5451 0000:00:06.0: BUG: , pos = 16384, buffer size = 16384, period size = 1024

It seems that folding the position offset is enough for fixing the
warning and no ill-effect has been seen by that.

Reported-by: Enrico Mioso <mrkiko.rs@...il.com>
Tested-by: Enrico Mioso <mrkiko.rs@...il.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/pci/ali5451/ali5451.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/sound/pci/ali5451/ali5451.c
+++ b/sound/pci/ali5451/ali5451.c
@@ -1422,6 +1422,7 @@ snd_ali_playback_pointer(struct snd_pcm_
 	spin_unlock(&codec->reg_lock);
 	snd_ali_printk("playback pointer returned cso=%xh.\n", cso);
 
+	cso %= runtime->buffer_size;
 	return cso;
 }
 
@@ -1442,6 +1443,7 @@ static snd_pcm_uframes_t snd_ali_pointer
 	cso = inw(ALI_REG(codec, ALI_CSO_ALPHA_FMS + 2));
 	spin_unlock(&codec->reg_lock);
 
+	cso %= runtime->buffer_size;
 	return cso;
 }