Re: [syzbot] Re: [PATCH v2] Bluetooth: hci_core: Fix sleeping function called from invalid context

From: syzbot
Date: Thu Dec 05 2024 - 10:13:26 EST

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Subject: Re: [PATCH v2] Bluetooth: hci_core: Fix sleeping function called from invalid context
Author: luiz.dentz@xxxxxxxxx

#syz test

On Wed, Dec 4, 2024 at 1:59 PM Luiz Augusto von Dentz
<luiz.dentz@xxxxxxxxx> wrote:
>
> Hi Pauli,
>
> On Wed, Dec 4, 2024 at 1:44 PM Pauli Virtanen <pav@xxxxxx> wrote:
> >
> > Hi Luiz,
> >
> > ke, 2024-12-04 kello 11:58 -0500, Luiz Augusto von Dentz kirjoitti:
> > > From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
> > >
> > > This reworks hci_cb_list to not use mutex hci_cb_list_lock to avoid bugs
> > > like the bellow:
> >
> > This also in principle allows callbacks to be still running on another
> > CPU when hci_unregister_cb() exits. Not sure if that is unwanted.
>
> Well hci_unregister_cb is only called if you unload the whole module
> e.g bt_exit, but you can't do that if the interface is not down afaik,
> so I don't think it is possible to hit the case where the copied
> entries would be invalid due to module being unloaded.
>
> > >
> > > BUG: sleeping function called from invalid context at kernel/locking/mutex.c:585
> > > in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 5070, name: kworker/u9:2
> > > preempt_count: 0, expected: 0
> > > RCU nest depth: 1, expected: 0
> > > 4 locks held by kworker/u9:2/5070:
> > > #0: ffff888015be3948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3229 [inline]
> > > #0: ffff888015be3948 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_scheduled_works+0x8e0/0x1770 kernel/workqueue.c:3335
> > > #1: ffffc90003b6fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3230 [inline]
> > > #1: ffffc90003b6fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x91b/0x1770 kernel/workqueue.c:3335
> > > #2: ffff8880665d0078 (&hdev->lock){+.+.}-{3:3}, at: hci_le_create_big_complete_evt+0xcf/0xae0 net/bluetooth/hci_event.c:6914
> > > #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
> > > #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
> > > #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: hci_le_create_big_complete_evt+0xdb/0xae0 net/bluetooth/hci_event.c:6915
> > > CPU: 0 PID: 5070 Comm: kworker/u9:2 Not tainted 6.8.0-syzkaller-08073-g480e035fc4c7 #0
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> > > Workqueue: hci0 hci_rx_work
> > > Call Trace:
> > > <TASK>
> > > __dump_stack lib/dump_stack.c:88 [inline]
> > > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
> > > __might_resched+0x5d4/0x780 kernel/sched/core.c:10187
> > > __mutex_lock_common kernel/locking/mutex.c:585 [inline]
> > > __mutex_lock+0xc1/0xd70 kernel/locking/mutex.c:752
> > > hci_connect_cfm include/net/bluetooth/hci_core.h:2004 [inline]
> > > hci_le_create_big_complete_evt+0x3d9/0xae0 net/bluetooth/hci_event.c:6939
> > > hci_event_func net/bluetooth/hci_event.c:7514 [inline]
> > > hci_event_packet+0xa53/0x1540 net/bluetooth/hci_event.c:7569
> > > hci_rx_work+0x3e8/0xca0 net/bluetooth/hci_core.c:4171
> > > process_one_work kernel/workqueue.c:3254 [inline]
> > > process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335
> > > worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
> > > kthread+0x2f0/0x390 kernel/kthread.c:388
> > > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
> > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
> > > </TASK>
> > >
> > > Reported-by: syzbot+2fb0835e0c9cefc34614@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > Closes: https://syzkaller.appspot.com/bug?extid=2fb0835e0c9cefc34614
> > > Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
> > > ---
> > > include/net/bluetooth/hci_core.h | 108 ++++++++++++++++++++-----------
> > > net/bluetooth/hci_core.c | 9 +--
> > > net/bluetooth/iso.c | 6 ++
> > > net/bluetooth/l2cap_core.c | 12 ++--
> > > net/bluetooth/rfcomm/core.c | 6 ++
> > > net/bluetooth/sco.c | 12 ++--
> > > 6 files changed, 97 insertions(+), 56 deletions(-)
> > >
> > > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> > > index ea798f07c5a2..ca22ead85dbe 100644
> > > --- a/include/net/bluetooth/hci_core.h
> > > +++ b/include/net/bluetooth/hci_core.h
> > > @@ -804,7 +804,6 @@ struct hci_conn_params {
> > > extern struct list_head hci_dev_list;
> > > extern struct list_head hci_cb_list;
> > > extern rwlock_t hci_dev_list_lock;
> > > -extern struct mutex hci_cb_list_lock;
> > >
> > > #define hci_dev_set_flag(hdev, nr) set_bit((nr), (hdev)->dev_flags)
> > > #define hci_dev_clear_flag(hdev, nr) clear_bit((nr), (hdev)->dev_flags)
> > > @@ -2017,24 +2016,47 @@ struct hci_cb {
> > >
> > > char *name;
> > >
> > > + bool (*match) (struct hci_conn *conn);
> > > void (*connect_cfm) (struct hci_conn *conn, __u8 status);
> > > void (*disconn_cfm) (struct hci_conn *conn, __u8 status);
> > > void (*security_cfm) (struct hci_conn *conn, __u8 status,
> > > - __u8 encrypt);
> > > + __u8 encrypt);
> > > void (*key_change_cfm) (struct hci_conn *conn, __u8 status);
> > > void (*role_switch_cfm) (struct hci_conn *conn, __u8 status, __u8 role);
> > > };
> > >
> > > +static inline void hci_cb_lookup(struct hci_conn *conn, struct list_head *list)
> > > +{
> > > + struct hci_cb *cb, *cpy;
> > > +
> > > + rcu_read_lock();
> > > + list_for_each_entry_rcu(cb, &hci_cb_list, list) {
> > > + if (cb->match && cb->match(conn)) {
> > > + cpy = kmalloc(sizeof(*cpy), GFP_ATOMIC);
> > > + if (!cpy)
> > > + break;
> > > +
> > > + *cpy = *cb;
> > > + INIT_LIST_HEAD(&cpy->list);
> > > + list_add_rcu(&cpy->list, list);
> > > + }
> > > + }
> > > + rcu_read_unlock();
> > > +}
> > > +
> > > static inline void hci_connect_cfm(struct hci_conn *conn, __u8 status)
> > > {
> > > - struct hci_cb *cb;
> > > + struct list_head list;
> > > + struct hci_cb *cb, *tmp;
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_for_each_entry(cb, &hci_cb_list, list) {
> > > + INIT_LIST_HEAD(&list);
> > > + hci_cb_lookup(conn, &list);
> > > +
> > > + list_for_each_entry_safe(cb, tmp, &list, list) {
> > > if (cb->connect_cfm)
> > > cb->connect_cfm(conn, status);
> > > + kfree(cb);
> > > }
> > > - mutex_unlock(&hci_cb_list_lock);
> > >
> > > if (conn->connect_cfm_cb)
> > > conn->connect_cfm_cb(conn, status);
> > > @@ -2042,22 +2064,43 @@ static inline void hci_connect_cfm(struct hci_conn *conn, __u8 status)
> > >
> > > static inline void hci_disconn_cfm(struct hci_conn *conn, __u8 reason)
> > > {
> > > - struct hci_cb *cb;
> > > + struct list_head list;
> > > + struct hci_cb *cb, *tmp;
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_for_each_entry(cb, &hci_cb_list, list) {
> > > + INIT_LIST_HEAD(&list);
> > > + hci_cb_lookup(conn, &list);
> > > +
> > > + list_for_each_entry_safe(cb, tmp, &list, list) {
> > > if (cb->disconn_cfm)
> > > cb->disconn_cfm(conn, reason);
> > > + kfree(cb);
> > > }
> > > - mutex_unlock(&hci_cb_list_lock);
> > >
> > > if (conn->disconn_cfm_cb)
> > > conn->disconn_cfm_cb(conn, reason);
> > > }
> > >
> > > +static inline void hci_security_cfm(struct hci_conn *conn, __u8 status,
> > > + __u8 encrypt)
> > > +{
> > > + struct list_head list;
> > > + struct hci_cb *cb, *tmp;
> > > +
> > > + INIT_LIST_HEAD(&list);
> > > + hci_cb_lookup(conn, &list);
> > > +
> > > + list_for_each_entry_safe(cb, tmp, &list, list) {
> > > + if (cb->security_cfm)
> > > + cb->security_cfm(conn, status, encrypt);
> > > + kfree(cb);
> > > + }
> > > +
> > > + if (conn->security_cfm_cb)
> > > + conn->security_cfm_cb(conn, status);
> > > +}
> > > +
> > > static inline void hci_auth_cfm(struct hci_conn *conn, __u8 status)
> > > {
> > > - struct hci_cb *cb;
> > > __u8 encrypt;
> > >
> > > if (test_bit(HCI_CONN_ENCRYPT_PEND, &conn->flags))
> > > @@ -2065,20 +2108,11 @@ static inline void hci_auth_cfm(struct hci_conn *conn, __u8 status)
> > >
> > > encrypt = test_bit(HCI_CONN_ENCRYPT, &conn->flags) ? 0x01 : 0x00;
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_for_each_entry(cb, &hci_cb_list, list) {
> > > - if (cb->security_cfm)
> > > - cb->security_cfm(conn, status, encrypt);
> > > - }
> > > - mutex_unlock(&hci_cb_list_lock);
> > > -
> > > - if (conn->security_cfm_cb)
> > > - conn->security_cfm_cb(conn, status);
> > > + hci_security_cfm(conn, status, encrypt);
> > > }
> > >
> > > static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
> > > {
> > > - struct hci_cb *cb;
> > > __u8 encrypt;
> > >
> > > if (conn->state == BT_CONFIG) {
> > > @@ -2105,40 +2139,38 @@ static inline void hci_encrypt_cfm(struct hci_conn *conn, __u8 status)
> > > conn->sec_level = conn->pending_sec_level;
> > > }
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_for_each_entry(cb, &hci_cb_list, list) {
> > > - if (cb->security_cfm)
> > > - cb->security_cfm(conn, status, encrypt);
> > > - }
> > > - mutex_unlock(&hci_cb_list_lock);
> > > -
> > > - if (conn->security_cfm_cb)
> > > - conn->security_cfm_cb(conn, status);
> > > + hci_security_cfm(conn, status, encrypt);
> > > }
> > >
> > > static inline void hci_key_change_cfm(struct hci_conn *conn, __u8 status)
> > > {
> > > - struct hci_cb *cb;
> > > + struct list_head list;
> > > + struct hci_cb *cb, *tmp;
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_for_each_entry(cb, &hci_cb_list, list) {
> > > + INIT_LIST_HEAD(&list);
> > > + hci_cb_lookup(conn, &list);
> > > +
> > > + list_for_each_entry_safe(cb, tmp, &list, list) {
> > > if (cb->key_change_cfm)
> > > cb->key_change_cfm(conn, status);
> > > + kfree(cb);
> > > }
> > > - mutex_unlock(&hci_cb_list_lock);
> > > }
> > >
> > > static inline void hci_role_switch_cfm(struct hci_conn *conn, __u8 status,
> > > __u8 role)
> > > {
> > > - struct hci_cb *cb;
> > > + struct list_head list;
> > > + struct hci_cb *cb, *tmp;
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_for_each_entry(cb, &hci_cb_list, list) {
> > > + INIT_LIST_HEAD(&list);
> > > + hci_cb_lookup(conn, &list);
> > > +
> > > + list_for_each_entry_safe(cb, tmp, &list, list) {
> > > if (cb->role_switch_cfm)
> > > cb->role_switch_cfm(conn, status, role);
> > > + kfree(cb);
> > > }
> > > - mutex_unlock(&hci_cb_list_lock);
> > > }
> > >
> > > static inline bool hci_bdaddr_is_rpa(bdaddr_t *bdaddr, u8 addr_type)
> > > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > > index f9e19f9cb5a3..25d180d225c1 100644
> > > --- a/net/bluetooth/hci_core.c
> > > +++ b/net/bluetooth/hci_core.c
> > > @@ -2993,9 +2993,7 @@ int hci_register_cb(struct hci_cb *cb)
> > > {
> > > BT_DBG("%p name %s", cb, cb->name);
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_add_tail(&cb->list, &hci_cb_list);
> > > - mutex_unlock(&hci_cb_list_lock);
> > > + list_add_tail_rcu(&cb->list, &hci_cb_list);
> > >
> > > return 0;
> > > }
> > > @@ -3005,9 +3003,8 @@ int hci_unregister_cb(struct hci_cb *cb)
> > > {
> > > BT_DBG("%p name %s", cb, cb->name);
> > >
> > > - mutex_lock(&hci_cb_list_lock);
> > > - list_del(&cb->list);
> > > - mutex_unlock(&hci_cb_list_lock);
> > > + list_del_rcu(&cb->list);
> > > + synchronize_rcu();
> > >
> > > return 0;
> > > }
> > > diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
> > > index 8ed818254dc8..eccdaa16cba0 100644
> > > --- a/net/bluetooth/iso.c
> > > +++ b/net/bluetooth/iso.c
> > > @@ -2154,6 +2154,11 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
> > > return HCI_LM_ACCEPT;
> > > }
> > >
> > > +static bool iso_match(struct hci_conn *hcon)
> > > +{
> > > + return hcon->type == ISO_LINK || hcon->type == LE_LINK;
> > > +}
> > > +
> > > static void iso_connect_cfm(struct hci_conn *hcon, __u8 status)
> > > {
> > > if (hcon->type != ISO_LINK) {
> > > @@ -2335,6 +2340,7 @@ void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
> > >
> > > static struct hci_cb iso_cb = {
> > > .name = "ISO",
> > > + .match = iso_match,
> > > .connect_cfm = iso_connect_cfm,
> > > .disconn_cfm = iso_disconn_cfm,
> > > };
> > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > > index 6544c1ed7143..27b4c4a2ba1f 100644
> > > --- a/net/bluetooth/l2cap_core.c
> > > +++ b/net/bluetooth/l2cap_core.c
> > > @@ -7217,6 +7217,11 @@ static struct l2cap_chan *l2cap_global_fixed_chan(struct l2cap_chan *c,
> > > return NULL;
> > > }
> > >
> > > +static bool l2cap_match(struct hci_conn *hcon)
> > > +{
> > > + return hcon->type == ACL_LINK || hcon->type == LE_LINK;
> > > +}
> > > +
> > > static void l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
> > > {
> > > struct hci_dev *hdev = hcon->hdev;
> > > @@ -7224,9 +7229,6 @@ static void l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
> > > struct l2cap_chan *pchan;
> > > u8 dst_type;
> > >
> > > - if (hcon->type != ACL_LINK && hcon->type != LE_LINK)
> > > - return;
> > > -
> > > BT_DBG("hcon %p bdaddr %pMR status %d", hcon, &hcon->dst, status);
> > >
> > > if (status) {
> > > @@ -7291,9 +7293,6 @@ int l2cap_disconn_ind(struct hci_conn *hcon)
> > >
> > > static void l2cap_disconn_cfm(struct hci_conn *hcon, u8 reason)
> > > {
> > > - if (hcon->type != ACL_LINK && hcon->type != LE_LINK)
> > > - return;
> > > -
> > > BT_DBG("hcon %p reason %d", hcon, reason);
> > >
> > > l2cap_conn_del(hcon, bt_to_errno(reason));
> > > @@ -7572,6 +7571,7 @@ void l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
> > >
> > > static struct hci_cb l2cap_cb = {
> > > .name = "L2CAP",
> > > + .match = l2cap_match,
> > > .connect_cfm = l2cap_connect_cfm,
> > > .disconn_cfm = l2cap_disconn_cfm,
> > > .security_cfm = l2cap_security_cfm,
> > > diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
> > > index ad5177e3a69b..4c56ca5a216c 100644
> > > --- a/net/bluetooth/rfcomm/core.c
> > > +++ b/net/bluetooth/rfcomm/core.c
> > > @@ -2134,6 +2134,11 @@ static int rfcomm_run(void *unused)
> > > return 0;
> > > }
> > >
> > > +static bool rfcomm_match(struct hci_conn *hcon)
> > > +{
> > > + return hcon->type == ACL_LINK;
> > > +}
> > > +
> > > static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt)
> > > {
> > > struct rfcomm_session *s;
> > > @@ -2180,6 +2185,7 @@ static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt)
> > >
> > > static struct hci_cb rfcomm_cb = {
> > > .name = "RFCOMM",
> > > + .match = rfcomm_match,
> > > .security_cfm = rfcomm_security_cfm
> > > };
> > >
> > > diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
> > > index 7eb8d3e04ec4..40c4957cfc0b 100644
> > > --- a/net/bluetooth/sco.c
> > > +++ b/net/bluetooth/sco.c
> > > @@ -1397,11 +1397,13 @@ int sco_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
> > > return lm;
> > > }
> > >
> > > +static bool sco_match(struct hci_conn *hcon)
> > > +{
> > > + return hcon->type == SCO_LINK || hcon->type == ESCO_LINK;
> > > +}
> > > +
> > > static void sco_connect_cfm(struct hci_conn *hcon, __u8 status)
> > > {
> > > - if (hcon->type != SCO_LINK && hcon->type != ESCO_LINK)
> > > - return;
> > > -
> > > BT_DBG("hcon %p bdaddr %pMR status %u", hcon, &hcon->dst, status);
> > >
> > > if (!status) {
> > > @@ -1416,9 +1418,6 @@ static void sco_connect_cfm(struct hci_conn *hcon, __u8 status)
> > >
> > > static void sco_disconn_cfm(struct hci_conn *hcon, __u8 reason)
> > > {
> > > - if (hcon->type != SCO_LINK && hcon->type != ESCO_LINK)
> > > - return;
> > > -
> > > BT_DBG("hcon %p reason %d", hcon, reason);
> > >
> > > sco_conn_del(hcon, bt_to_errno(reason));
> > > @@ -1444,6 +1443,7 @@ void sco_recv_scodata(struct hci_conn *hcon, struct sk_buff *skb)
> > >
> > > static struct hci_cb sco_cb = {
> > > .name = "SCO",
> > > + .match = sco_match,
> > > .connect_cfm = sco_connect_cfm,
> > > .disconn_cfm = sco_disconn_cfm,
> > > };
> >
>
>
> --
> Luiz Augusto von Dentz

--
Luiz Augusto von Dentz

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