diff options
| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2021-07-27 06:12:04 +0900 |
|---|---|---|
| committer | Luiz Augusto von Dentz <luiz.von.dentz@intel.com> | 2021-07-28 15:42:21 -0700 |
| commit | 58ce6d5b271ab25fb2056f84a8e5546945eb5fc9 (patch) | |
| tree | 8edd01c55756b2c0021d8e18a2b9ae3880ec0df4 /net/bluetooth/hci_core.c | |
| parent | acd5aea400494ce960904cca4626dfbbe307dd47 (diff) | |
Bluetooth: defer cleanup of resources in hci_unregister_dev()
syzbot is hitting might_sleep() warning at hci_sock_dev_event()
due to calling lock_sock() with rw spinlock held [1].
It seems that history of this locking problem is a trial and error.
Commit b40df5743ee8aed8 ("[PATCH] bluetooth: fix socket locking in
hci_sock_dev_event()") in 2.6.21-rc4 changed bh_lock_sock() to lock_sock()
as an attempt to fix lockdep warning.
Then, commit 4ce61d1c7a8ef4c1 ("[BLUETOOTH]: Fix locking in
hci_sock_dev_event().") in 2.6.22-rc2 changed lock_sock() to
local_bh_disable() + bh_lock_sock_nested() as an attempt to fix
sleep in atomic context warning.
Then, commit 4b5dd696f81b210c ("Bluetooth: Remove local_bh_disable() from
hci_sock.c") in 3.3-rc1 removed local_bh_disable().
Then, commit e305509e678b3a4a ("Bluetooth: use correct lock to prevent UAF
of hdev object") in 5.13-rc5 again changed bh_lock_sock_nested() to
lock_sock() as an attempt to fix CVE-2021-3573.
This difficulty comes from current implementation that
hci_sock_dev_event(HCI_DEV_UNREG) is responsible for dropping all
references from sockets because hci_unregister_dev() immediately reclaims
resources as soon as returning from hci_sock_dev_event(HCI_DEV_UNREG).
But the history suggests that hci_sock_dev_event(HCI_DEV_UNREG) was not
doing what it should do.
Therefore, instead of trying to detach sockets from device, let's accept
not detaching sockets from device at hci_sock_dev_event(HCI_DEV_UNREG),
by moving actual cleanup of resources from hci_unregister_dev() to
hci_release_dev() which is called by bt_host_release when all references
to this unregistered device (which is a kobject) are gone.
Link: https://syzkaller.appspot.com/bug?extid=a5df189917e79d5e59c9 [1]
Reported-by: syzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Fixes: e305509e678b3a4a ("Bluetooth: use correct lock to prevent UAF of hdev object")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Diffstat (limited to 'net/bluetooth/hci_core.c')
| -rw-r--r-- | net/bluetooth/hci_core.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 2560ed2f144d..2b78e1336c53 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -3996,14 +3996,10 @@ EXPORT_SYMBOL(hci_register_dev); /* Unregister HCI device */ void hci_unregister_dev(struct hci_dev *hdev) { - int id; - BT_DBG("%p name %s bus %d", hdev, hdev->name, hdev->bus); hci_dev_set_flag(hdev, HCI_UNREGISTER); - id = hdev->id; - write_lock(&hci_dev_list_lock); list_del(&hdev->list); write_unlock(&hci_dev_list_lock); @@ -4038,7 +4034,13 @@ void hci_unregister_dev(struct hci_dev *hdev) } device_del(&hdev->dev); + hci_dev_put(hdev); +} +EXPORT_SYMBOL(hci_unregister_dev); +/* Release HCI device */ +void hci_release_dev(struct hci_dev *hdev) +{ debugfs_remove_recursive(hdev->debugfs); kfree_const(hdev->hw_info); kfree_const(hdev->fw_info); @@ -4063,11 +4065,10 @@ void hci_unregister_dev(struct hci_dev *hdev) hci_blocked_keys_clear(hdev); hci_dev_unlock(hdev); - hci_dev_put(hdev); - - ida_simple_remove(&hci_index_ida, id); + ida_simple_remove(&hci_index_ida, hdev->id); + kfree(hdev); } -EXPORT_SYMBOL(hci_unregister_dev); +EXPORT_SYMBOL(hci_release_dev); /* Suspend HCI device */ int hci_suspend_dev(struct hci_dev *hdev) |