Messages in this thread | | | Date | Fri, 11 Sep 2015 15:11:32 +0300 | From | Jarkko Nikula <> | Subject | Re: [PATCH] spi: spidev: fix possible NULL dereference |
| |
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@vectorindia.org> > --- > 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@vger.kernel.org>
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@linux.intel.com> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
| |