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Subject[PATCH 1/2] gpio: gpio-grgpio: fix possible sleep-in-atomic-context bugs in grgpio_remove()
Date
The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/gpio/gpiolib-sysfs.c, 796:
mutex_lock in gpiochip_sysfs_unregister
drivers/gpio/gpiolib.c, 1455:
gpiochip_sysfs_unregister in gpiochip_remove
drivers/gpio/gpio-grgpio.c, 460:
gpiochip_remove in grgpio_remove
drivers/gpio/gpio-grgpio.c, 449:
_raw_spin_lock_irqsave in grgpio_remove

kernel/irq/irqdomain.c, 243:
mutex_lock in irq_domain_remove
drivers/gpio/gpio-grgpio.c, 463:
irq_domain_remove in grgpio_remove
drivers/gpio/gpio-grgpio.c, 449:
_raw_spin_lock_irqsave in grgpio_remove

mutex_lock() can sleep at runtime.

To fix these bugs, gpiochip_remove() and irq_domain_remove() are called
without holding the spinlock.

These bugs are found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
drivers/gpio/gpio-grgpio.c | 5 ++++-
sound/soc/sti/uniperif_player.c | 3 ++-
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index 08234e64993a..60a2871c5ba7 100644
--- a/drivers/gpio/gpio-grgpio.c
+++ b/drivers/gpio/gpio-grgpio.c
@@ -448,13 +448,16 @@ static int grgpio_remove(struct platform_device *ofdev)
}
}

+ spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
+
gpiochip_remove(&priv->gc);

if (priv->domain)
irq_domain_remove(priv->domain);

out:
- spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
+ if (ret)
+ spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);

return ret;
}
diff --git a/sound/soc/sti/uniperif_player.c b/sound/soc/sti/uniperif_player.c
index 48ea915b24ba..62244e207679 100644
--- a/sound/soc/sti/uniperif_player.c
+++ b/sound/soc/sti/uniperif_player.c
@@ -601,13 +601,14 @@ static int uni_player_ctl_iec958_put(struct snd_kcontrol *kcontrol,
mutex_unlock(&player->ctrl_lock);

spin_lock_irqsave(&player->irq_lock, flags);
+ spin_unlock_irqrestore(&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;
}

--
2.17.1
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