From: Zhenzhong Duan zhenzhong.duan@gmail.com
[ 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@gmail.com Link: https://lore.kernel.org/r/20200618032125.4650-2-zhenzhong.duan@gmail.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 88d0976215fac..ac6bf1fbbfe68 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -605,15 +605,20 @@ static int spidev_open(struct inode *inode, struct file *filp) 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; @@ -621,19 +626,14 @@ 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);