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tty: don't leak cdev in tty_cdev_add()

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Commit a3a10ce342 ("Avoid usb reset crashes by making tty_io cdevs truly
dynamic") which mixes using cdev_alloc() and cdev_init() is problematic.
Subsequent call to cdev_init() after cdev_alloc() sets kobj release method
from cdev_dynamic_release() to cdev_default_release() and thus makes it
impossible to free allocated cdev.

This patch also consolidates error path of cdev_add() as cdev can also leak
here if things went wrong.

Signed-off-by: Leon Yu <chianglungyu@gmail.com>
Fixes: a3a10ce342 ("Avoid usb reset crashes by making tty_io cdevs truly dynamic")
Acked-by: Richard Watts <rrw@kynesim.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Leon Yu 2015-09-07 13:08:37 +00:00 committed by Greg Kroah-Hartman
parent 0c727a4204
commit c1a752ba2d
1 changed files with 7 additions and 2 deletions
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9
drivers/tty/tty_io.c
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@ -3151,13 +3151,18 @@ struct class *tty_class;
static int tty_cdev_add(struct tty_driver *driver, dev_t dev, static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
unsigned int index, unsigned int count) unsigned int index, unsigned int count)
{ {
int err;
/* init here, since reused cdevs cause crashes */ /* init here, since reused cdevs cause crashes */
driver->cdevs[index] = cdev_alloc(); driver->cdevs[index] = cdev_alloc();
if (!driver->cdevs[index]) if (!driver->cdevs[index])
return -ENOMEM; return -ENOMEM;
cdev_init(driver->cdevs[index], &tty_fops); driver->cdevs[index]->ops = &tty_fops;
driver->cdevs[index]->owner = driver->owner; driver->cdevs[index]->owner = driver->owner;
return cdev_add(driver->cdevs[index], dev, count); err = cdev_add(driver->cdevs[index], dev, count);
if (err)
kobject_put(&driver->cdevs[index]->kobj);
return err;
} }
/** /**