Hi On 09/10/2015 02:18 PM, Sudip Mukherjee wrote:
During the last close we are freeing spidev if spidev->spi is NULL, but just before checking if spidev->spi is NULL we are dereferencing it. Lets add a check there to avoid the NULL dereference. Signed-off-by: Sudip Mukherjee <sudip@xxxxxxxxxxxxxxx> --- drivers/spi/spidev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index fba92a5..ef008e5 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -651,7 +651,8 @@ static int spidev_release(struct inode *inode, struct file *filp) kfree(spidev->rx_buffer); spidev->rx_buffer = NULL; - spidev->speed_hz = spidev->spi->max_speed_hz; + if (spidev->spi) + spidev->speed_hz = spidev->spi->max_speed_hz; /* ... after we unbound from the underlying device? */ spin_lock_irq(&spidev->spi_lock);
Actually this fixes a *real* NULL dereference case but it is not related to normal open/close life cycle of spidev. It requires that spidev is kept open when SPI master is removed.
spidev->spi is set to NULL in spidev_remove() and it is called before spidev_release() in case master is removed while spidev is in use
It would be good to update this to commit log, add a tag below and Cc <stable@xxxxxxxxxxxxxxx>
Fixes: 9169051617df ("spi: spidev: Don't mangle max_speed_hz in underlying spi device")
You can add these too: Reviewed-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx> Tested-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
