diff options
| author | Lin Ma <linma@zju.edu.cn> | 2021-11-16 18:27:32 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-11-18 07:17:05 +0300 |
| commit | 48b71a9e66c2eab60564b1b1c85f4928ed04e406 (patch) | |
| tree | 9d1b2d6dac9054a61e5a19bd3e734b29b5ef8c82 | |
| parent | 3e3b5dfcd16a3e254aab61bd1e8c417dd4503102 (diff) | |
| download | linux-48b71a9e66c2eab60564b1b1c85f4928ed04e406.tar.xz | |
NFC: add NCI_UNREG flag to eliminate the race
There are two sites that calls queue_work() after the
destroy_workqueue() and lead to possible UAF.
The first site is nci_send_cmd(), which can happen after the
nci_close_device as below
nfcmrvl_nci_unregister_dev | nfc_genl_dev_up
nci_close_device |
flush_workqueue |
del_timer_sync |
nci_unregister_device | nfc_get_device
destroy_workqueue | nfc_dev_up
nfc_unregister_device | nci_dev_up
device_del | nci_open_device
| __nci_request
| nci_send_cmd
| queue_work !!!
Another site is nci_cmd_timer, awaked by the nci_cmd_work from the
nci_send_cmd.
... | ...
nci_unregister_device | queue_work
destroy_workqueue |
nfc_unregister_device | ...
device_del | nci_cmd_work
| mod_timer
| ...
| nci_cmd_timer
| queue_work !!!
For the above two UAF, the root cause is that the nfc_dev_up can race
between the nci_unregister_device routine. Therefore, this patch
introduce NCI_UNREG flag to easily eliminate the possible race. In
addition, the mutex_lock in nci_close_device can act as a barrier.
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211116152732.19238-1-linma@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/net/nfc/nci_core.h | 1 | ||||
| -rw-r--r-- | net/nfc/nci/core.c | 19 |
2 files changed, 18 insertions, 2 deletions
diff --git a/include/net/nfc/nci_core.h b/include/net/nfc/nci_core.h index a964daedc17b..ea8595651c38 100644 --- a/include/net/nfc/nci_core.h +++ b/include/net/nfc/nci_core.h @@ -30,6 +30,7 @@ enum nci_flag { NCI_UP, NCI_DATA_EXCHANGE, NCI_DATA_EXCHANGE_TO, + NCI_UNREG, }; /* NCI device states */ diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c index 1dd0269c1a72..d2537383a3e8 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -476,6 +476,11 @@ static int nci_open_device(struct nci_dev *ndev) mutex_lock(&ndev->req_lock); + if (test_bit(NCI_UNREG, &ndev->flags)) { + rc = -ENODEV; + goto done; + } + if (test_bit(NCI_UP, &ndev->flags)) { rc = -EALREADY; goto done; @@ -548,6 +553,10 @@ done: static int nci_close_device(struct nci_dev *ndev) { nci_req_cancel(ndev, ENODEV); + + /* This mutex needs to be held as a barrier for + * caller nci_unregister_device + */ mutex_lock(&ndev->req_lock); if (!test_and_clear_bit(NCI_UP, &ndev->flags)) { @@ -585,8 +594,8 @@ static int nci_close_device(struct nci_dev *ndev) del_timer_sync(&ndev->cmd_timer); - /* Clear flags */ - ndev->flags = 0; + /* Clear flags except NCI_UNREG */ + ndev->flags &= BIT(NCI_UNREG); mutex_unlock(&ndev->req_lock); @@ -1269,6 +1278,12 @@ void nci_unregister_device(struct nci_dev *ndev) { struct nci_conn_info *conn_info, *n; + /* This set_bit is not protected with specialized barrier, + * However, it is fine because the mutex_lock(&ndev->req_lock); + * in nci_close_device() will help to emit one. + */ + set_bit(NCI_UNREG, &ndev->flags); + nci_close_device(ndev); destroy_workqueue(ndev->cmd_wq); |