drivers/nfc/nfcmrvl/main.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
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 <duoming@zju.edu.cn>
---
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);
--
2.17.1Hello, 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 <duoming@zju.edu.cn> 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 <duoming@zju.edu.cn> > > 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
On 10/04/2022 15:52, 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; > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Best regards, Krzysztof
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