blob: b03a92d3db32ed5c4f451bc871c3ccadc069ba81 [file] [log] [blame]
From 0abba41d66c0e9fbb0958e7c6ea14cc93afe13b2 Mon Sep 17 00:00:00 2001
From: Jia-Ju Bai <baijiaju1990@gmail.com>
Date: Wed, 18 Dec 2019 17:44:05 +0800
Subject: [PATCH] uio: fix a sleep-in-atomic-context bug in
uio_dmem_genirq_irqcontrol()
commit b74351287d4bd90636c3f48bc188c2f53824c2d4 upstream.
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@gmail.com>
Link: https://lore.kernel.org/r/20191218094405.6009-1-baijiaju1990@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/uio/uio_dmem_genirq.c b/drivers/uio/uio_dmem_genirq.c
index f32cef94aa82..53c58813ec08 100644
--- a/drivers/uio/uio_dmem_genirq.c
+++ b/drivers/uio/uio_dmem_genirq.c
@@ -132,11 +132,13 @@ 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;
}
--
2.7.4