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Subject[PATCH AUTOSEL 5.5 050/542] gpio: gpio-grgpio: fix possible sleep-in-atomic-context bugs in grgpio_irq_map/unmap()
Date
From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit e36eaf94be8f7bc4e686246eed3cf92d845e2ef8 ]

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/gpio/gpio-grgpio.c, 261:
request_irq in grgpio_irq_map
drivers/gpio/gpio-grgpio.c, 255:
_raw_spin_lock_irqsave in grgpio_irq_map

drivers/gpio/gpio-grgpio.c, 318:
free_irq in grgpio_irq_unmap
drivers/gpio/gpio-grgpio.c, 299:
_raw_spin_lock_irqsave in grgpio_irq_unmap

request_irq() and free_irq() can sleep at runtime.

To fix these bugs, request_irq() and free_irq() 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>
Link: https://lore.kernel.org/r/20191218132605.10594-1-baijiaju1990@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpio/gpio-grgpio.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index 08234e64993a9..3224933f4c8f4 100644
--- a/drivers/gpio/gpio-grgpio.c
+++ b/drivers/gpio/gpio-grgpio.c
@@ -253,17 +253,16 @@ static int grgpio_irq_map(struct irq_domain *d, unsigned int irq,
lirq->irq = irq;
uirq = &priv->uirqs[lirq->index];
if (uirq->refcnt == 0) {
+ spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
ret = request_irq(uirq->uirq, grgpio_irq_handler, 0,
dev_name(priv->dev), priv);
if (ret) {
dev_err(priv->dev,
"Could not request underlying irq %d\n",
uirq->uirq);
-
- spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
-
return ret;
}
+ spin_lock_irqsave(&priv->gc.bgpio_lock, flags);
}
uirq->refcnt++;

@@ -309,8 +308,11 @@ static void grgpio_irq_unmap(struct irq_domain *d, unsigned int irq)
if (index >= 0) {
uirq = &priv->uirqs[lirq->index];
uirq->refcnt--;
- if (uirq->refcnt == 0)
+ if (uirq->refcnt == 0) {
+ spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
free_irq(uirq->uirq, priv);
+ return;
+ }
}

spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
--
2.20.1
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