lkml.org 
[lkml]   [2019]   [Feb]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [RFC v1 2/3] max17042_battery: fix potential user-after-free on module unload
On Tue, Feb 5, 2019 at 3:27 AM Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
>
> Are there many more instances of this?

Unfortunately I think so.
A simple grep brings up a couple of candidates, but I'm sure there are more:

drivers/regulator/arizona-micsupp.c
drivers/nfc/port100.c
drivers/power/supply/max14656_charger_detector.c
drivers/phy/broadcom/phy-bcm-ns2-usbdrd.c

> I am unsure if we need
> devm_init_work() when we can easily do the same in remove() call.

The devm_init_work() suggestion only addresses the problem for those modules
that use devm_. The others will need fixes in remove(). But this is not as
elegant and error-proof as using devm_init_work().

For example, take port100.c's disconnect function. It starts deallocating
resources, but the cmd_complete_work (scheduled by urb completion) may still
be in progress, and touch these resources after free.

At least, I _think_ that is the case. I'm not familiar enough with this driver
to be 100% sure, but it sounds likely.

static void port100_disconnect(struct usb_interface *interface)
{
struct port100 *dev;

dev = usb_get_intfdata(interface);
usb_set_intfdata(interface, NULL);

nfc_digital_unregister_device(dev->nfc_digital_dev);
nfc_digital_free_device(dev->nfc_digital_dev);

usb_kill_urb(dev->in_urb);
usb_kill_urb(dev->out_urb);

usb_free_urb(dev->in_urb);
usb_free_urb(dev->out_urb);
usb_put_dev(dev->udev);

kfree(dev->cmd);

nfc_info(&interface->dev, "Sony Port-100 NFC device disconnected\n");
}

\
 
 \ /
  Last update: 2019-02-05 15:29    [W:0.080 / U:0.584 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site