From: Oliver Neukum Date: Thu, 8 Feb 2007 14:42:53 +0000 (+0100) Subject: USB: fix autosuspend race in skeleton driver X-Git-Tag: v2.6.21-rc1~82^2~23 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5b06470816fb5e658e81db2a55b530ff2ba711c9;p=linux-2.6 USB: fix autosuspend race in skeleton driver as the skeleton driver was made ready for autosuspend a race condition was introduced. The reference to get device must be gotten before the autosuspend counter is upped, as this operation may sleep, dropping BKL. Dropping BKL means that the pointer to the device may become invalid. Here's the fix. Signed-off-by: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index 296b091cf1..46929a1b6f 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -90,13 +90,15 @@ static int skel_open(struct inode *inode, struct file *file) goto exit; } + /* increment our usage count for the device */ + kref_get(&dev->kref); + /* prevent the device from being autosuspended */ retval = usb_autopm_get_interface(interface); - if (retval) + if (retval) { + kref_put(&dev->kref, skel_delete); goto exit; - - /* increment our usage count for the device */ - kref_get(&dev->kref); + } /* save our object in the file's private structure */ file->private_data = dev;