From: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx> [ Upstream commit 06096cc6c5a84ced929634b0d79376b94c65a4bd ] 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@xxxxxxxxx> Link: https://lore.kernel.org/r/20200618032125.4650-2-zhenzhong.duan@xxxxxxxxx Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/spi/spidev.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index 5edf4029a3486..167047760d79a 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -607,15 +607,20 @@ 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; @@ -623,19 +628,14 @@ 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); -- 2.25.1
