diff mbox series

[v4] Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync

Message ID 20230814190101.2302448-1-luiz.dentz@gmail.com
State New
Headers show
Series [v4] Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync | expand

Commit Message

Luiz Augusto von Dentz Aug. 14, 2023, 7:01 p.m. UTC 
From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

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@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 net/bluetooth/hci_sync.c | 55 +++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 20 deletions(-)

Comments

Luiz Augusto von Dentz Aug. 15, 2023, 10:41 p.m. UTC | #1 
Hi Pauli,

On Mon, Aug 14, 2023 at 12:01 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
>
> 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@iki.fi>
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> ---
>  net/bluetooth/hci_sync.c | 55 +++++++++++++++++++++++++---------------
>  1 file changed, 35 insertions(+), 20 deletions(-)
>
> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> index 5eb30ba21370..d10a0f36b947 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 +5390,57 @@ 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;
>         }
>
> +       hci_dev_lock(hdev);
> +
> +       /* 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) {
> +               err = 0;
> +               goto unlock;
> +       }
> +
>         /* 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_conn_failed(conn, reason);
>
> +unlock:
> +       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

Any comments on this one, I actually took the time to add some tests
to iso-tester to attempt to cover scenarios where
hci_disconnect_all_sync is called whiled connecting/connected which
seems to be working with these changes.
Pauli Virtanen Aug. 16, 2023, 5:54 p.m. UTC | #2 
Hi Luiz,

ti, 2023-08-15 kello 15:41 -0700, Luiz Augusto von Dentz kirjoitti:
> Hi Pauli,
> 
> On Mon, Aug 14, 2023 at 12:01 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> > 
> > From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> > 
> > 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@iki.fi>
> > Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> > ---
> >  net/bluetooth/hci_sync.c | 55 +++++++++++++++++++++++++---------------
> >  1 file changed, 35 insertions(+), 20 deletions(-)
> > 
> > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> > index 5eb30ba21370..d10a0f36b947 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 +5390,57 @@ 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;
> >         }
> > 
> > +       hci_dev_lock(hdev);
> > +
> > +       /* 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) {
> > +               err = 0;
> > +               goto unlock;
> > +       }
> > +
> >         /* 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_conn_failed(conn, reason);
> > 
> > +unlock:
> > +       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
> 
> Any comments on this one, I actually took the time to add some tests
> to iso-tester to attempt to cover scenarios where
> hci_disconnect_all_sync is called whiled connecting/connected which
> seems to be working with these changes.
> 

I don't have further comments. I tested it on the load that previously
generated KASAN crashes, and haven't seen any so far.

I guess the only question was if deleting conns in hdev->req_workqueue
could trigger some crash in hdev->workqueue processing not protected by
locks/refcount, but don't know a scenario how this would occur right
now.
Luiz Augusto von Dentz Aug. 16, 2023, 5:59 p.m. UTC | #3 
Hi Pauli,

On Wed, Aug 16, 2023 at 10:54 AM Pauli Virtanen <pav@iki.fi> wrote:
>
> Hi Luiz,
>
> ti, 2023-08-15 kello 15:41 -0700, Luiz Augusto von Dentz kirjoitti:
> > Hi Pauli,
> >
> > On Mon, Aug 14, 2023 at 12:01 PM Luiz Augusto von Dentz
> > <luiz.dentz@gmail.com> wrote:
> > >
> > > From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> > >
> > > 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@iki.fi>
> > > Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> > > ---
> > >  net/bluetooth/hci_sync.c | 55 +++++++++++++++++++++++++---------------
> > >  1 file changed, 35 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> > > index 5eb30ba21370..d10a0f36b947 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 +5390,57 @@ 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;
> > >         }
> > >
> > > +       hci_dev_lock(hdev);
> > > +
> > > +       /* 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) {
> > > +               err = 0;
> > > +               goto unlock;
> > > +       }
> > > +
> > >         /* 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_conn_failed(conn, reason);
> > >
> > > +unlock:
> > > +       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
> >
> > Any comments on this one, I actually took the time to add some tests
> > to iso-tester to attempt to cover scenarios where
> > hci_disconnect_all_sync is called whiled connecting/connected which
> > seems to be working with these changes.
> >
>
> I don't have further comments. I tested it on the load that previously
> generated KASAN crashes, and haven't seen any so far.

Great, I will push these changes then.

> I guess the only question was if deleting conns in hdev->req_workqueue
> could trigger some crash in hdev->workqueue processing not protected by
> locks/refcount, but don't know a scenario how this would occur right
> now.

Yeah, let's keep monitoring and perhaps add more tests to try and
reproduce different scenarios.
patchwork-bot+bluetooth@kernel.org Aug. 16, 2023, 7:20 p.m. UTC | #4 
Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Mon, 14 Aug 2023 12:01:01 -0700 you wrote:
> From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> 
> 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.
> 
> [...]

Here is the summary with links:
  - [v4] Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync
    https://git.kernel.org/bluetooth/bluetooth-next/c/45c37c4e9c9a

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 5eb30ba21370..d10a0f36b947 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 +5390,57 @@  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;
 	}
 
+	hci_dev_lock(hdev);
+
+	/* 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) {
+		err = 0;
+		goto unlock;
+	}
+
 	/* 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_conn_failed(conn, reason);
 
+unlock:
+	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;
 }