From: Ian Abbott Date: Tue, 4 Dec 2012 15:59:55 +0000 (+0000) Subject: staging: comedi: prevent auto-unconfig of manually configured devices X-Git-Tag: v3.2.46~2 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2e4b48300640fd023e2644142ff11da6e88e9aa2;p=pandora-kernel.git staging: comedi: prevent auto-unconfig of manually configured devices commit 7d3135af399e92cf4c9bbc5f86b6c140aab3b88c upstream. When a low-level comedi driver auto-configures a device, a `struct comedi_dev_file_info` is allocated (as well as a `struct comedi_device`) by `comedi_alloc_board_minor()`. A pointer to the hardware `struct device` is stored as a cookie in the `struct comedi_dev_file_info`. When the low-level comedi driver auto-unconfigures the device, `comedi_auto_unconfig()` uses the cookie to find the `struct comedi_dev_file_info` so it can detach the comedi device from the driver, clean it up and free it. A problem arises if the user manually unconfigures and reconfigures the comedi device using the `COMEDI_DEVCONFIG` ioctl so that is no longer associated with the original hardware device. The problem is that the cookie is not cleared, so that a call to `comedi_auto_unconfig()` from the low-level driver will still find it, detach it, clean it up and free it. Stop this problem occurring by always clearing the `hardware_device` cookie in the `struct comedi_dev_file_info` whenever the `COMEDI_DEVCONFIG` ioctl call is successful. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index a023f522408d..fe4dbf3af2ed 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -143,6 +143,9 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd, } rc = do_devconfig_ioctl(dev, (struct comedi_devconfig __user *)arg); + if (rc == 0) + /* Evade comedi_auto_unconfig(). */ + dev_file_info->hardware_device = NULL; goto done; }