* [PATCH v2] Input: powermate - fix use-after-free in powermate_config_complete
@ 2023-10-01 15:35 Javier Carrasco
2023-10-04 14:30 ` Dmitry Torokhov
0 siblings, 1 reply; 2+ messages in thread
From: Javier Carrasco @ 2023-10-01 15:35 UTC (permalink / raw)
To: Dmitry Torokhov
Cc: linux-input, linux-kernel, Javier Carrasco, syzbot+0434ac83f907a1dbdd1e
syzbot has found a use-after-free bug [1] in the powermate driver. This
happens when the device is disconnected, which leads to a memory free
from the powermate_device struct.
When an asynchronous control message completes after the kfree and its
callback is invoked, the lock does not exist anymore and hence the bug.
Use usb_kill_urb() on pm->config to cancel any in-progress requests upon
device disconnection. Given that this action is already done on pm->irq,
reorder the code to have both calls after the call to
input_unregister_device(), which is the most common approach.
[1] https://syzkaller.appspot.com/bug?extid=0434ac83f907a1dbdd1e
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reported-by: syzbot+0434ac83f907a1dbdd1e@syzkaller.appspotmail.com
---
Changes in v2:
- Use usb_kill_urb() on pm->config upon device disconnection.
- Link to v1: https://lore.kernel.org/r/20230916-topic-powermate_use_after_free-v1-1-2ffa46652869@gmail.com
---
drivers/input/misc/powermate.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/input/misc/powermate.c b/drivers/input/misc/powermate.c
index c1c733a9cb89..c0aea75eb087 100644
--- a/drivers/input/misc/powermate.c
+++ b/drivers/input/misc/powermate.c
@@ -423,8 +423,9 @@ static void powermate_disconnect(struct usb_interface *intf)
usb_set_intfdata(intf, NULL);
if (pm) {
pm->requires_update = 0;
- usb_kill_urb(pm->irq);
input_unregister_device(pm->input);
+ usb_kill_urb(pm->irq);
+ usb_kill_urb(pm->config);
usb_free_urb(pm->irq);
usb_free_urb(pm->config);
powermate_free_buffers(interface_to_usbdev(intf), pm);
---
base-commit: cefc06e4de1477dbdc3cb2a91d4b1873b7797a5c
change-id: 20230916-topic-powermate_use_after_free-c703c7969c91
Best regards,
--
Javier Carrasco <javier.carrasco.cruz@gmail.com>
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] Input: powermate - fix use-after-free in powermate_config_complete
2023-10-01 15:35 [PATCH v2] Input: powermate - fix use-after-free in powermate_config_complete Javier Carrasco
@ 2023-10-04 14:30 ` Dmitry Torokhov
0 siblings, 0 replies; 2+ messages in thread
From: Dmitry Torokhov @ 2023-10-04 14:30 UTC (permalink / raw)
To: Javier Carrasco; +Cc: linux-input, linux-kernel, syzbot+0434ac83f907a1dbdd1e
Hi Javier,
On Sun, Oct 01, 2023 at 05:35:54PM +0200, Javier Carrasco wrote:
> syzbot has found a use-after-free bug [1] in the powermate driver. This
> happens when the device is disconnected, which leads to a memory free
> from the powermate_device struct.
> When an asynchronous control message completes after the kfree and its
> callback is invoked, the lock does not exist anymore and hence the bug.
>
> Use usb_kill_urb() on pm->config to cancel any in-progress requests upon
> device disconnection. Given that this action is already done on pm->irq,
> reorder the code to have both calls after the call to
> input_unregister_device(), which is the most common approach.
>
> [1] https://syzkaller.appspot.com/bug?extid=0434ac83f907a1dbdd1e
>
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
> Reported-by: syzbot+0434ac83f907a1dbdd1e@syzkaller.appspotmail.com
> ---
> Changes in v2:
> - Use usb_kill_urb() on pm->config upon device disconnection.
> - Link to v1: https://lore.kernel.org/r/20230916-topic-powermate_use_after_free-v1-1-2ffa46652869@gmail.com
> ---
> drivers/input/misc/powermate.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/misc/powermate.c b/drivers/input/misc/powermate.c
> index c1c733a9cb89..c0aea75eb087 100644
> --- a/drivers/input/misc/powermate.c
> +++ b/drivers/input/misc/powermate.c
> @@ -423,8 +423,9 @@ static void powermate_disconnect(struct usb_interface *intf)
> usb_set_intfdata(intf, NULL);
> if (pm) {
> pm->requires_update = 0;
> - usb_kill_urb(pm->irq);
No, you do not want interrupts coming in while input device is being
destroyed, this one needs to stay where it is.
> input_unregister_device(pm->input);
> + usb_kill_urb(pm->irq);
> + usb_kill_urb(pm->config);
> usb_free_urb(pm->irq);
> usb_free_urb(pm->config);
> powermate_free_buffers(interface_to_usbdev(intf), pm);
Thanks.
--
Dmitry
^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-10-01 15:35 [PATCH v2] Input: powermate - fix use-after-free in powermate_config_complete Javier Carrasco
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