| Message ID | 20220409135854.33333-1-duoming@zju.edu.cn (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | drivers: nfc: nfcmrvl: fix UAF bug in nfcmrvl_nci_unregister_dev() | expand |
On 09/04/2022 15:58, Duoming Zhou wrote: > There is a potential UAF bug in nfcmrvl usb driver between > unregister and resume operation. > > The race that cause that UAF 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 > | skb_queue_tail > nfcmrvl_disconnect | > nfcmrvl_nci_unregister_dev | > nfcmrvl_fw_dnld_deinit | ... > destroy_workqueue //(1) | > ... | queue_work //(2) > > When nfcmrvl usb driver is resuming, we detach the device. > The workqueue is destroyed in position (1), but it will be > latter used in position (2), which leads to data race. I miss here something. How can you queue work on a destroyed workqueue? When workqueue is destroyed, no more work should be executed. Unless you mean the case that draining the work (during destroying, not after) causes the (2) to happen? > This patch reorders the nfcmrvl_fw_dnld_deinit after > nci_unregister_device in order to prevent UAF. Because > nci_unregister_device will not return until finish all > operations from upper layer. > > Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> > --- > 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..5ed17b23ee8 100644 > --- a/drivers/nfc/nfcmrvl/main.c > +++ b/drivers/nfc/nfcmrvl/main.c > @@ -186,12 +186,11 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *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); > > nci_unregister_device(ndev); > + nfcmrvl_fw_dnld_deinit(priv); The new order matches reverse-probe, so actually makes sense. > nci_free_device(ndev); > kfree(priv); > } Best regards, Krzysztof
Hello, I am sorry for the delay. On Sat, 9 Apr 2022 17:10:05 +0200 Krzysztof Kozlowski wrote: > > There is a potential UAF bug in nfcmrvl usb driver between > > unregister and resume operation. > > > > The race that cause that UAF 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 > > | skb_queue_tail > > nfcmrvl_disconnect | > > nfcmrvl_nci_unregister_dev | > > nfcmrvl_fw_dnld_deinit | ... > > destroy_workqueue //(1) | > > ... | queue_work //(2) > > > > When nfcmrvl usb driver is resuming, we detach the device. > > The workqueue is destroyed in position (1), but it will be > > latter used in position (2), which leads to data race. > > I miss here something. How can you queue work on a destroyed workqueue? > When workqueue is destroyed, no more work should be executed. Unless you > mean the case that draining the work (during destroying, not after) > causes the (2) to happen? Sorry, I make a mistake in my patch. The destroy_workqueue() will not return until all work is finished. So the UAF bug is not exist. Actually, there is a double free bug in nfcmrvl_nci_unregister_dev(). The root cause is shown 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) | ... | 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 deallocate again in position (2), which leads to double free. > > This patch reorders the nfcmrvl_fw_dnld_deinit after > > nci_unregister_device in order to prevent UAF. Because > > nci_unregister_device will not return until finish all > > operations from upper layer. > > > > Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> > > --- > > 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..5ed17b23ee8 100644 > > --- a/drivers/nfc/nfcmrvl/main.c > > +++ b/drivers/nfc/nfcmrvl/main.c > > @@ -186,12 +186,11 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *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); > > > > nci_unregister_device(ndev); > > + nfcmrvl_fw_dnld_deinit(priv); > > The new order matches reverse-probe, so actually makes sense. > > > nci_free_device(ndev); > > kfree(priv); > > } I will send "[PATCH] drivers: nfc: nfcmrvl: fix double free bug in nfcmrvl_nci_unregister_dev()" as soon as possible. Best regards, Duoming Zhou
On 10/04/2022 10:30, duoming@zju.edu.cn wrote: (...) > > (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) | > ... | 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 deallocate again in position (2), which > leads to double free. Indeed. The code looks racy. It uses the fw_download_in_progress variable which in core is partially protected with device_lock(). Moving code around might not solve the issue entirely because there is no synchronization here. > >>> This patch reorders the nfcmrvl_fw_dnld_deinit after >>> nci_unregister_device in order to prevent UAF. Because >>> nci_unregister_device will not return until finish all >>> operations from upper layer. >>> >>> Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> >>> --- >>> 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..5ed17b23ee8 100644 >>> --- a/drivers/nfc/nfcmrvl/main.c >>> +++ b/drivers/nfc/nfcmrvl/main.c >>> @@ -186,12 +186,11 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *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); >>> >>> nci_unregister_device(ndev); >>> + nfcmrvl_fw_dnld_deinit(priv); >> >> The new order matches reverse-probe, so actually makes sense. >> >>> nci_free_device(ndev); >>> kfree(priv); >>> } > > I will send "[PATCH] drivers: nfc: nfcmrvl: fix double free bug in > nfcmrvl_nci_unregister_dev()" as soon as possible. Thanks! Best regards, Krzysztof
diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c index 2fcf545012b..5ed17b23ee8 100644 --- a/drivers/nfc/nfcmrvl/main.c +++ b/drivers/nfc/nfcmrvl/main.c @@ -186,12 +186,11 @@ void nfcmrvl_nci_unregister_dev(struct nfcmrvl_private *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); nci_unregister_device(ndev); + nfcmrvl_fw_dnld_deinit(priv); nci_free_device(ndev); kfree(priv); }
There is a potential UAF bug in nfcmrvl usb driver between unregister and resume operation. The race that cause that UAF 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 | skb_queue_tail nfcmrvl_disconnect | nfcmrvl_nci_unregister_dev | nfcmrvl_fw_dnld_deinit | ... destroy_workqueue //(1) | ... | queue_work //(2) When nfcmrvl usb driver is resuming, we detach the device. The workqueue is destroyed in position (1), but it will be latter used in position (2), which leads to data race. This patch reorders the nfcmrvl_fw_dnld_deinit after nci_unregister_device in order to prevent UAF. Because nci_unregister_device will not return until finish all operations from upper layer. Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- drivers/nfc/nfcmrvl/main.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)