From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Zhenzhong Duan <zhenzhong.duan@gmail.com>,
Mark Brown <broonie@kernel.org>, Sasha Levin <sashal@kernel.org>,
linux-spi@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 04/13] spi: spidev: fix a race between spidev_release and spidev_remove
Date: Wed, 1 Jul 2020 21:27:03 -0400 [thread overview]
Message-ID: <20200702012712.2701986-4-sashal@kernel.org> (raw)
In-Reply-To: <20200702012712.2701986-1-sashal@kernel.org>
From: Zhenzhong Duan <zhenzhong.duan@gmail.com>
[ Upstream commit abd42781c3d2155868821f1b947ae45bbc33330d ]
Imagine below scene, spidev is referenced after it's freed.
spidev_release() spidev_remove()
...
spin_lock_irq(&spidev->spi_lock);
spidev->spi = NULL;
spin_unlock_irq(&spidev->spi_lock);
mutex_lock(&device_list_lock);
dofree = (spidev->spi == NULL);
if (dofree)
kfree(spidev);
mutex_unlock(&device_list_lock);
mutex_lock(&device_list_lock);
list_del(&spidev->device_entry);
device_destroy(spidev_class, spidev->devt);
clear_bit(MINOR(spidev->devt), minors);
if (spidev->users == 0)
kfree(spidev);
mutex_unlock(&device_list_lock);
Fix it by resetting spidev->spi in device_list_lock's protection.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
Link: https://lore.kernel.org/r/20200618032125.4650-1-zhenzhong.duan@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spidev.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index a685c6114a8d5..67ad7e46da42d 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -809,13 +809,13 @@ static int spidev_remove(struct spi_device *spi)
{
struct spidev_data *spidev = spi_get_drvdata(spi);
+ /* prevent new opens */
+ mutex_lock(&device_list_lock);
/* make sure ops on existing fds can abort cleanly */
spin_lock_irq(&spidev->spi_lock);
spidev->spi = NULL;
spin_unlock_irq(&spidev->spi_lock);
- /* prevent new opens */
- mutex_lock(&device_list_lock);
list_del(&spidev->device_entry);
device_destroy(spidev_class, spidev->devt);
clear_bit(MINOR(spidev->devt), minors);
--
2.25.1
next parent reply other threads:[~2020-07-02 1:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200702012712.2701986-1-sashal@kernel.org>
2020-07-02 1:27 ` Sasha Levin [this message]
2020-07-02 1:27 ` [PATCH AUTOSEL 4.9 05/13] spi: spidev: fix a potential use-after-free in spidev_release() Sasha Levin
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