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Message-Id: <20200214161147.15842-27-sashal@kernel.org>
Date: Fri, 14 Feb 2020 11:08:02 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Jia-Ju Bai <baijiaju1990@...il.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 027/252] uio: fix a sleep-in-atomic-context bug in uio_dmem_genirq_irqcontrol()
From: Jia-Ju Bai <baijiaju1990@...il.com>
[ Upstream commit b74351287d4bd90636c3f48bc188c2f53824c2d4 ]
The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:
kernel/irq/manage.c, 523:
synchronize_irq in disable_irq
drivers/uio/uio_dmem_genirq.c, 140:
disable_irq in uio_dmem_genirq_irqcontrol
drivers/uio/uio_dmem_genirq.c, 134:
_raw_spin_lock_irqsave in uio_dmem_genirq_irqcontrol
synchronize_irq() can sleep at runtime.
To fix this bug, disable_irq() is called without holding the spinlock.
This bug is found by a static analysis tool STCheck written by myself.
Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
Link: https://lore.kernel.org/r/20191218094405.6009-1-baijiaju1990@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/uio/uio_dmem_genirq.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/uio/uio_dmem_genirq.c b/drivers/uio/uio_dmem_genirq.c
index e1134a4d97f3f..a00b4aee6c799 100644
--- a/drivers/uio/uio_dmem_genirq.c
+++ b/drivers/uio/uio_dmem_genirq.c
@@ -135,11 +135,13 @@ static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
if (irq_on) {
if (test_and_clear_bit(0, &priv->flags))
enable_irq(dev_info->irq);
+ spin_unlock_irqrestore(&priv->lock, flags);
} else {
- if (!test_and_set_bit(0, &priv->flags))
+ if (!test_and_set_bit(0, &priv->flags)) {
+ spin_unlock_irqrestore(&priv->lock, flags);
disable_irq(dev_info->irq);
+ }
}
- spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
--
2.20.1
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