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| author | Zhenzhong Duan <zhenzhong.duan@gmail.com> | 2020-06-18 11:21:25 +0800 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2020-06-18 17:47:00 +0100 |
| commit | 06096cc6c5a84ced929634b0d79376b94c65a4bd (patch) | |
| tree | 20308a74b1a841161edebc9abcf1f566bfae01ca | |
| parent | abd42781c3d2155868821f1b947ae45bbc33330d (diff) | |
spi: spidev: fix a potential use-after-free in spidev_release()
If an spi device is unbounded from the driver before the release
process, there will be an NULL pointer reference when it's
referenced in spi_slave_abort().
Fix it by checking it's already freed before reference.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
Link: https://lore.kernel.org/r/20200618032125.4650-2-zhenzhong.duan@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
| -rw-r--r-- | drivers/spi/spidev.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index f74ea26c382f..59e07675ef86 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -609,15 +609,20 @@ err_find_dev: static int spidev_release(struct inode *inode, struct file *filp) { struct spidev_data *spidev; + int dofree; mutex_lock(&device_list_lock); spidev = filp->private_data; filp->private_data = NULL; + spin_lock_irq(&spidev->spi_lock); + /* ... after we unbound from the underlying device? */ + dofree = (spidev->spi == NULL); + spin_unlock_irq(&spidev->spi_lock); + /* last close? */ spidev->users--; if (!spidev->users) { - int dofree; kfree(spidev->tx_buffer); spidev->tx_buffer = NULL; @@ -625,19 +630,14 @@ static int spidev_release(struct inode *inode, struct file *filp) kfree(spidev->rx_buffer); spidev->rx_buffer = NULL; - spin_lock_irq(&spidev->spi_lock); - if (spidev->spi) - spidev->speed_hz = spidev->spi->max_speed_hz; - - /* ... after we unbound from the underlying device? */ - dofree = (spidev->spi == NULL); - spin_unlock_irq(&spidev->spi_lock); - if (dofree) kfree(spidev); + else + spidev->speed_hz = spidev->spi->max_speed_hz; } #ifdef CONFIG_SPI_SLAVE - spi_slave_abort(spidev->spi); + if (!dofree) + spi_slave_abort(spidev->spi); #endif mutex_unlock(&device_list_lock); |