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ASoC: STI: Fix null ptr deference in IRQ handler
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With RTlinux a race condition has been found that leads to NULL ptr crash:
- On CPU 0: uni_player_irq_handler is called to treat XRUN
 "(player->state == UNIPERIF_STATE_STOPPED)" is FALSE so status is checked,
 dev_err(player->dev, "FIFO underflow error detected") is printed
and then snd_pcm_stream_lock should be called to lock stream for stopping.
- On CPU 1: application stop and close the stream.
Issue is that the stop and shutdown functions are executed while
"FIFO underflow error detected" is printed.
So when CPU 0 calls snd_pcm_stream_lock, player->substream is already null.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
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@arnopo @broonie
arnopo authored and broonie committed Apr 6, 2017
1 parent 3c9d3f1 commit d05d862
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Showing 3 changed files with 45 additions and 15 deletions.
1 change: 1 addition & 0 deletions sound/soc/sti/uniperif.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1299,6 +1299,7 @@ struct uniperif {
int ver; /* IP version, used by register access macros */
struct regmap_field *clk_sel;
struct regmap_field *valid_sel;
spinlock_t irq_lock; /* use to prevent race condition with IRQ */

/* capabilities */
const struct snd_pcm_hardware *hw;
Expand Down
35 changes: 24 additions & 11 deletions sound/soc/sti/uniperif_player.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -65,10 +65,13 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id)
unsigned int status;
unsigned int tmp;

if (player->state == UNIPERIF_STATE_STOPPED) {
/* Unexpected IRQ: do nothing */
return IRQ_NONE;
}
spin_lock(&player->irq_lock);
if (!player->substream)
goto irq_spin_unlock;

snd_pcm_stream_lock(player->substream);
if (player->state == UNIPERIF_STATE_STOPPED)
goto stream_unlock;

/* Get interrupt status & clear them immediately */
status = GET_UNIPERIF_ITS(player);
Expand All @@ -88,9 +91,7 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id)
SET_UNIPERIF_ITM_BCLR_FIFO_ERROR(player);

/* Stop the player */
snd_pcm_stream_lock(player->substream);
snd_pcm_stop(player->substream, SNDRV_PCM_STATE_XRUN);
snd_pcm_stream_unlock(player->substream);
}

ret = IRQ_HANDLED;
Expand All @@ -104,9 +105,7 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id)
SET_UNIPERIF_ITM_BCLR_DMA_ERROR(player);

/* Stop the player */
snd_pcm_stream_lock(player->substream);
snd_pcm_stop(player->substream, SNDRV_PCM_STATE_XRUN);
snd_pcm_stream_unlock(player->substream);

ret = IRQ_HANDLED;
}
Expand All @@ -116,7 +115,8 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id)
if (!player->underflow_enabled) {
dev_err(player->dev,
"unexpected Underflow recovering\n");
return -EPERM;
ret = -EPERM;
goto stream_unlock;
}
/* Read the underflow recovery duration */
tmp = GET_UNIPERIF_STATUS_1_UNDERFLOW_DURATION(player);
Expand All @@ -138,13 +138,16 @@ static irqreturn_t uni_player_irq_handler(int irq, void *dev_id)
dev_err(player->dev, "Underflow recovery failed\n");

/* Stop the player */
snd_pcm_stream_lock(player->substream);
snd_pcm_stop(player->substream, SNDRV_PCM_STATE_XRUN);
snd_pcm_stream_unlock(player->substream);

ret = IRQ_HANDLED;
}

stream_unlock:
snd_pcm_stream_unlock(player->substream);
irq_spin_unlock:
spin_unlock(&player->irq_lock);

return ret;
}

Expand Down Expand Up @@ -588,6 +591,7 @@ static int uni_player_ctl_iec958_put(struct snd_kcontrol *kcontrol,
struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai);
struct uniperif *player = priv->dai_data.uni;
struct snd_aes_iec958 *iec958 = &player->stream_settings.iec958;
unsigned long flags;

mutex_lock(&player->ctrl_lock);
iec958->status[0] = ucontrol->value.iec958.status[0];
Expand All @@ -596,12 +600,14 @@ static int uni_player_ctl_iec958_put(struct snd_kcontrol *kcontrol,
iec958->status[3] = ucontrol->value.iec958.status[3];
mutex_unlock(&player->ctrl_lock);

spin_lock_irqsave(&player->irq_lock, flags);
if (player->substream && player->substream->runtime)
uni_player_set_channel_status(player,
player->substream->runtime);
else
uni_player_set_channel_status(player, NULL);

spin_unlock_irqrestore(&player->irq_lock, flags);
return 0;
}

Expand Down Expand Up @@ -686,9 +692,12 @@ static int uni_player_startup(struct snd_pcm_substream *substream,
{
struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai);
struct uniperif *player = priv->dai_data.uni;
unsigned long flags;
int ret;

spin_lock_irqsave(&player->irq_lock, flags);
player->substream = substream;
spin_unlock_irqrestore(&player->irq_lock, flags);

player->clk_adj = 0;

Expand Down Expand Up @@ -986,12 +995,15 @@ static void uni_player_shutdown(struct snd_pcm_substream *substream,
{
struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai);
struct uniperif *player = priv->dai_data.uni;
unsigned long flags;

spin_lock_irqsave(&player->irq_lock, flags);
if (player->state != UNIPERIF_STATE_STOPPED)
/* Stop the player */
uni_player_stop(player);

player->substream = NULL;
spin_unlock_irqrestore(&player->irq_lock, flags);
}

static int uni_player_parse_dt_audio_glue(struct platform_device *pdev,
Expand Down Expand Up @@ -1096,6 +1108,7 @@ int uni_player_init(struct platform_device *pdev,
}

mutex_init(&player->ctrl_lock);
spin_lock_init(&player->irq_lock);

/* Ensure that disabled by default */
SET_UNIPERIF_CONFIG_BACK_STALL_REQ_DISABLE(player);
Expand Down
24 changes: 20 additions & 4 deletions sound/soc/sti/uniperif_reader.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,10 +46,15 @@ static irqreturn_t uni_reader_irq_handler(int irq, void *dev_id)
struct uniperif *reader = dev_id;
unsigned int status;

spin_lock(&reader->irq_lock);
if (!reader->substream)
goto irq_spin_unlock;

snd_pcm_stream_lock(reader->substream);
if (reader->state == UNIPERIF_STATE_STOPPED) {
/* Unexpected IRQ: do nothing */
dev_warn(reader->dev, "unexpected IRQ\n");
return IRQ_HANDLED;
goto stream_unlock;
}

/* Get interrupt status & clear them immediately */
Expand All @@ -60,13 +65,16 @@ static irqreturn_t uni_reader_irq_handler(int irq, void *dev_id)
if (unlikely(status & UNIPERIF_ITS_FIFO_ERROR_MASK(reader))) {
dev_err(reader->dev, "FIFO error detected\n");

snd_pcm_stream_lock(reader->substream);
snd_pcm_stop(reader->substream, SNDRV_PCM_STATE_XRUN);
snd_pcm_stream_unlock(reader->substream);

return IRQ_HANDLED;
ret = IRQ_HANDLED;
}

stream_unlock:
snd_pcm_stream_unlock(reader->substream);
irq_spin_unlock:
spin_unlock(&reader->irq_lock);

return ret;
}

Expand Down Expand Up @@ -347,9 +355,12 @@ static int uni_reader_startup(struct snd_pcm_substream *substream,
{
struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai);
struct uniperif *reader = priv->dai_data.uni;
unsigned long flags;
int ret;

spin_lock_irqsave(&reader->irq_lock, flags);
reader->substream = substream;
spin_unlock_irqrestore(&reader->irq_lock, flags);

if (!UNIPERIF_TYPE_IS_TDM(reader))
return 0;
Expand All @@ -375,12 +386,15 @@ static void uni_reader_shutdown(struct snd_pcm_substream *substream,
{
struct sti_uniperiph_data *priv = snd_soc_dai_get_drvdata(dai);
struct uniperif *reader = priv->dai_data.uni;
unsigned long flags;

spin_lock_irqsave(&reader->irq_lock, flags);
if (reader->state != UNIPERIF_STATE_STOPPED) {
/* Stop the reader */
uni_reader_stop(reader);
}
reader->substream = NULL;
spin_unlock_irqrestore(&reader->irq_lock, flags);
}

static const struct snd_soc_dai_ops uni_reader_dai_ops = {
Expand Down Expand Up @@ -415,6 +429,8 @@ int uni_reader_init(struct platform_device *pdev,
return -EBUSY;
}

spin_lock_init(&reader->irq_lock);

return 0;
}
EXPORT_SYMBOL_GPL(uni_reader_init);

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