From bf302ba15f9fc5fa2d84c6eaa2e740a0e0bb596b Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Tue, 4 Dec 2012 15:59:55 +0000 Subject: [PATCH] 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 --- drivers/staging/comedi/comedi_fops.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index d80b90fa2163..4242c2ec6470 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -138,6 +138,9 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd, if (cmd == COMEDI_DEVCONFIG) { 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; } -- 2.11.4.GIT