There is a potential double bug in nfcmrvl usb driver between
unregister and resume operation.
The race that cause that double free bug can be shown as below:
(FREE) | (USE)
| nfcmrvl_resume
| nfcmrvl_submit_bulk_urb
| nfcmrvl_bulk_complete
| nfcmrvl_nci_recv_frame
| nfcmrvl_fw_dnld_recv_frame
| queue_work
| fw_dnld_rx_work
| fw_dnld_over
| release_firmware
| kfree(fw); //(1)
nfcmrvl_disconnect |
nfcmrvl_nci_unregister_dev |
nfcmrvl_fw_dnld_abort |
fw_dnld_over | ...
if (priv->fw_dnld.fw) |
release_firmware |
kfree(fw); //(2) |
... | priv->fw_dnld.fw = NULL;
When nfcmrvl usb driver is resuming, we detach the device.
The release_firmware() will deallocate firmware in position (1),
but firmware will be deallocated again in position (2), which
leads to double free.
This patch reorders nfcmrvl_fw_dnld_deinit() before nfcmrvl_fw_dnld_abort()
in order to prevent double free bug. Because destroy_workqueue() will
not return until all work items are finished. The priv->fw_dnld.fw will
be set to NULL after work items are finished and fw_dnld_over() called by
nfcmrvl_nci_unregister_dev() will check whether priv->fw_dnld.fw is NULL.
So the double free bug could be prevented.
Signed-off-by: Duoming Zhou <[email protected]>
---
Changes in V2:
- Make commit message more clearer.
drivers/nfc/nfcmrvl/main.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c
index 2fcf545012b..d8342271f50 100644
--- a/drivers/nfc/nfcmrvl/main.c
+++ b/drivers/nfc/nfcmrvl/main.c
@@ -183,11 +183,10 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *priv)
{
struct nci_dev *ndev = priv->ndev;
+ nfcmrvl_fw_dnld_deinit(priv);
if (priv->ndev->nfc_dev->fw_download_in_progress)
nfcmrvl_fw_dnld_abort(priv);
- nfcmrvl_fw_dnld_deinit(priv);
-
if (gpio_is_valid(priv->config.reset_n_io))
gpio_free(priv->config.reset_n_io);
--
2.17.1
Hello,
On Sun, 2022-04-10 at 21:52 +0800, Duoming Zhou wrote:
> There is a potential double bug in nfcmrvl usb driver between
> unregister and resume operation.
>
> The race that cause that double free bug can be shown as below:
>
> (FREE) | (USE)
> | nfcmrvl_resume
> | nfcmrvl_submit_bulk_urb
> | nfcmrvl_bulk_complete
> | nfcmrvl_nci_recv_frame
> | nfcmrvl_fw_dnld_recv_frame
> | queue_work
> | fw_dnld_rx_work
> | fw_dnld_over
> | release_firmware
> | kfree(fw); //(1)
> nfcmrvl_disconnect |
> nfcmrvl_nci_unregister_dev |
> nfcmrvl_fw_dnld_abort |
> fw_dnld_over | ...
> if (priv->fw_dnld.fw) |
> release_firmware |
> kfree(fw); //(2) |
> ... | priv->fw_dnld.fw = NULL;
>
> When nfcmrvl usb driver is resuming, we detach the device.
> The release_firmware() will deallocate firmware in position (1),
> but firmware will be deallocated again in position (2), which
> leads to double free.
>
> This patch reorders nfcmrvl_fw_dnld_deinit() before nfcmrvl_fw_dnld_abort()
> in order to prevent double free bug. Because destroy_workqueue() will
> not return until all work items are finished. The priv->fw_dnld.fw will
> be set to NULL after work items are finished and fw_dnld_over() called by
> nfcmrvl_nci_unregister_dev() will check whether priv->fw_dnld.fw is NULL.
> So the double free bug could be prevented.
>
> Signed-off-by: Duoming Zhou <[email protected]>
This looks like a -net candidates, could you please add a suitable
fixes tag?
Thanks!
Paolo
Hello,
On Tue, 12 Apr 2022 00:28:16 -0700 Paolo Abeni wrote:
> > There is a potential double bug in nfcmrvl usb driver between
> > unregister and resume operation.
> >
> > The race that cause that double free bug can be shown as below:
> >
> > (FREE) | (USE)
> > | nfcmrvl_resume
> > | nfcmrvl_submit_bulk_urb
> > | nfcmrvl_bulk_complete
> > | nfcmrvl_nci_recv_frame
> > | nfcmrvl_fw_dnld_recv_frame
> > | queue_work
> > | fw_dnld_rx_work
> > | fw_dnld_over
> > | release_firmware
> > | kfree(fw); //(1)
> > nfcmrvl_disconnect |
> > nfcmrvl_nci_unregister_dev |
> > nfcmrvl_fw_dnld_abort |
> > fw_dnld_over | ...
> > if (priv->fw_dnld.fw) |
> > release_firmware |
> > kfree(fw); //(2) |
> > ... | priv->fw_dnld.fw = NULL;
> >
> > When nfcmrvl usb driver is resuming, we detach the device.
> > The release_firmware() will deallocate firmware in position (1),
> > but firmware will be deallocated again in position (2), which
> > leads to double free.
> >
> > This patch reorders nfcmrvl_fw_dnld_deinit() before nfcmrvl_fw_dnld_abort()
> > in order to prevent double free bug. Because destroy_workqueue() will
> > not return until all work items are finished. The priv->fw_dnld.fw will
> > be set to NULL after work items are finished and fw_dnld_over() called by
> > nfcmrvl_nci_unregister_dev() will check whether priv->fw_dnld.fw is NULL.
> > So the double free bug could be prevented.
> >
> > Signed-off-by: Duoming Zhou <[email protected]>
>
> This looks like a -net candidates, could you please add a suitable
> fixes tag?
I found my patch is not a comprehensive fix, because the fw_dnld_timeout()
could also reach fw_dnld_over(), which leads to double free bugs among
fw_dnld_rx_work(), fw_dnld_timeout() and nfcmrvl_nci_unregister_dev().
I sent a patch set "Fix double free bugs in nfcmrvl module" just now, and add
a fixes tag in it.
Best regards,
Duoming Zhou