From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Use-after-free can occur in hci_disconnect_all_sync if a connection is
deleted by concurrent processing of a controller event.
To prevent this the code now tries to iterate over the list backwards
to ensure the links are cleanup before its parents, also it no longer
relies on a cursor, instead it always uses the last element since
hci_abort_conn_sync is guaranteed to call hci_conn_del.
UAF crash log:
==================================================================
BUG: KASAN: slab-use-after-free in hci_set_powered_sync
(net/bluetooth/hci_sync.c:5424) [bluetooth]
Read of size 8 at addr ffff888009d9c000 by task kworker/u9:0/124
CPU: 0 PID: 124 Comm: kworker/u9:0 Tainted: G W
6.5.0-rc1+ #10
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
1.16.2-1.fc38 04/01/2014
Workqueue: hci0 hci_cmd_sync_work [bluetooth]
Call Trace:
<TASK>
dump_stack_lvl+0x5b/0x90
print_report+0xcf/0x670
? __virt_addr_valid+0xdd/0x160
? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth]
kasan_report+0xa6/0xe0
? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth]
? __pfx_set_powered_sync+0x10/0x10 [bluetooth]
hci_set_powered_sync+0x2c9/0x4a0 [bluetooth]
? __pfx_hci_set_powered_sync+0x10/0x10 [bluetooth]
? __pfx_lock_release+0x10/0x10
? __pfx_set_powered_sync+0x10/0x10 [bluetooth]
hci_cmd_sync_work+0x137/0x220 [bluetooth]
process_one_work+0x526/0x9d0
? __pfx_process_one_work+0x10/0x10
? __pfx_do_raw_spin_lock+0x10/0x10
? mark_held_locks+0x1a/0x90
worker_thread+0x92/0x630
? __pfx_worker_thread+0x10/0x10
kthread+0x196/0x1e0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x2c/0x50
</TASK>
Allocated by task 1782:
kasan_save_stack+0x33/0x60
kasan_set_track+0x25/0x30
__kasan_kmalloc+0x8f/0xa0
hci_conn_add+0xa5/0xa80 [bluetooth]
hci_bind_cis+0x881/0x9b0 [bluetooth]
iso_connect_cis+0x121/0x520 [bluetooth]
iso_sock_connect+0x3f6/0x790 [bluetooth]
__sys_connect+0x109/0x130
__x64_sys_connect+0x40/0x50
do_syscall_64+0x60/0x90
entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Freed by task 695:
kasan_save_stack+0x33/0x60
kasan_set_track+0x25/0x30
kasan_save_free_info+0x2b/0x50
__kasan_slab_free+0x10a/0x180
__kmem_cache_free+0x14d/0x2e0
device_release+0x5d/0xf0
kobject_put+0xdf/0x270
hci_disconn_complete_evt+0x274/0x3a0 [bluetooth]
hci_event_packet+0x579/0x7e0 [bluetooth]
hci_rx_work+0x287/0xaa0 [bluetooth]
process_one_work+0x526/0x9d0
worker_thread+0x92/0x630
kthread+0x196/0x1e0
ret_from_fork+0x2c/0x50
==================================================================
Fixes: 182ee45da083 ("Bluetooth: hci_sync: Rework hci_suspend_notifier")
Signed-off-by: Pauli Virtanen <pav@xxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
net/bluetooth/hci_sync.c | 51 ++++++++++++++++++++++++----------------
1 file changed, 31 insertions(+), 20 deletions(-)
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 5eb30ba21370..86e18e09136e 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5370,6 +5370,7 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason)
{
int err = 0;
u16 handle = conn->handle;
+ struct hci_conn *c;
switch (conn->state) {
case BT_CONNECTED:
@@ -5389,43 +5390,53 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason)
hci_dev_unlock(hdev);
return 0;
default:
+ hci_dev_lock(hdev);
conn->state = BT_CLOSED;
+ hci_disconn_cfm(conn, reason);
+ hci_conn_del(conn);
+ hci_dev_unlock(hdev);
return 0;
}
+ /* Check if the connection hasn't been cleanup while waiting
+ * commands to complete.
+ */
+ c = hci_conn_hash_lookup_handle(hdev, handle);
+ if (!c || c != conn)
+ return 0;
+
/* Cleanup hci_conn object if it cannot be cancelled as it
* likelly means the controller and host stack are out of sync
* or in case of LE it was still scanning so it can be cleanup
* safely.
*/
- if (err) {
- struct hci_conn *c;
-
- /* Check if the connection hasn't been cleanup while waiting
- * commands to complete.
- */
- c = hci_conn_hash_lookup_handle(hdev, handle);
- if (!c || c != conn)
- return 0;
-
- hci_dev_lock(hdev);
- hci_conn_failed(conn, err);
- hci_dev_unlock(hdev);
- }
+ hci_dev_lock(hdev);
+ hci_conn_failed(conn, reason);
+ hci_dev_unlock(hdev);
return err;
}
static int hci_disconnect_all_sync(struct hci_dev *hdev, u8 reason)
{
- struct hci_conn *conn, *tmp;
- int err;
+ struct list_head *head = &hdev->conn_hash.list;
+ struct hci_conn *conn;
- list_for_each_entry_safe(conn, tmp, &hdev->conn_hash.list, list) {
- err = hci_abort_conn_sync(hdev, conn, reason);
- if (err)
- return err;
+ rcu_read_lock();
+ while ((conn = list_first_or_null_rcu(head, struct hci_conn, list))) {
+ /* Make sure the connection is not freed while unlocking */
+ conn = hci_conn_get(conn);
+ rcu_read_unlock();
+ /* Disregard possible errors since hci_conn_del shall have been
+ * called even in case of errors had occurred since it would
+ * then cause hci_conn_failed to be called which calls
+ * hci_conn_del internally.
+ */
+ hci_abort_conn_sync(hdev, conn, reason);
+ hci_conn_put(conn);
+ rcu_read_lock();
}
+ rcu_read_unlock();
return 0;
}
--
2.41.0
