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Bluetooth: L2CAP: Fix deadlock
This fixes the following deadlock introduced by 39a92a55be13 ("bluetooth/l2cap: sync sock recv cb and release") ============================================ WARNING: possible recursive locking detected 6.10.0-rc3-g4029dba6b6f1 #6823 Not tainted -------------------------------------------- kworker/u5:0/35 is trying to acquire lock: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_sock_recv_cb+0x44/0x1e0 but task is already holding lock: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_get_chan_by_scid+0xaf/0xd0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&chan->lock#2/1); lock(&chan->lock#2/1); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u5:0/35: #0: ffff888002b8a940 ((wq_completion)hci0#2){+.+.}-{0:0}, at: process_one_work+0x750/0x930 #1: ffff888002c67dd0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x44e/0x930 #2: ffff888002ec2510 (&chan->lock#2/1){+.+.}-{3:3}, at: l2cap_get_chan_by_scid+0xaf/0xd0 To fix the original problem this introduces l2cap_chan_lock at l2cap_conless_channel to ensure that l2cap_sock_recv_cb is called with chan->lock held. Fixes: 89e856e ("bluetooth/l2cap: sync sock recv cb and release") Signed-off-by: Luiz Augusto von Dentz <[email protected]>
1 parent 1cc18c2 commit f1a8f40

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5 files changed

+37
-66
lines changed

5 files changed

+37
-66
lines changed

‎include/net/bluetooth/hci_sync.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,8 @@ int __hci_cmd_sync_status(struct hci_dev *hdev, u16 opcode, u32 plen,
3838
int __hci_cmd_sync_status_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
3939
const void *param, u8 event, u32 timeout,
4040
struct sock *sk);
41+
int hci_cmd_sync_status(struct hci_dev *hdev, u16 opcode, u32 plen,
42+
const void *param, u32 timeout);
4143

4244
void hci_cmd_sync_init(struct hci_dev *hdev);
4345
void hci_cmd_sync_clear(struct hci_dev *hdev);

‎net/bluetooth/hci_core.c‎

Lines changed: 18 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -63,50 +63,6 @@ DEFINE_MUTEX(hci_cb_list_lock);
6363
/* HCI ID Numbering */
6464
static DEFINE_IDA(hci_index_ida);
6565

66-
static int hci_scan_req(struct hci_request *req, unsigned long opt)
67-
{
68-
__u8 scan = opt;
69-
70-
BT_DBG("%s %x", req->hdev->name, scan);
71-
72-
/* Inquiry and Page scans */
73-
hci_req_add(req, HCI_OP_WRITE_SCAN_ENABLE, 1, &scan);
74-
return 0;
75-
}
76-
77-
static int hci_auth_req(struct hci_request *req, unsigned long opt)
78-
{
79-
__u8 auth = opt;
80-
81-
BT_DBG("%s %x", req->hdev->name, auth);
82-
83-
/* Authentication */
84-
hci_req_add(req, HCI_OP_WRITE_AUTH_ENABLE, 1, &auth);
85-
return 0;
86-
}
87-
88-
static int hci_encrypt_req(struct hci_request *req, unsigned long opt)
89-
{
90-
__u8 encrypt = opt;
91-
92-
BT_DBG("%s %x", req->hdev->name, encrypt);
93-
94-
/* Encryption */
95-
hci_req_add(req, HCI_OP_WRITE_ENCRYPT_MODE, 1, &encrypt);
96-
return 0;
97-
}
98-
99-
static int hci_linkpol_req(struct hci_request *req, unsigned long opt)
100-
{
101-
__le16 policy = cpu_to_le16(opt);
102-
103-
BT_DBG("%s %x", req->hdev->name, policy);
104-
105-
/* Default link policy */
106-
hci_req_add(req, HCI_OP_WRITE_DEF_LINK_POLICY, 2, &policy);
107-
return 0;
108-
}
109-
11066
/* Get HCI device by index.
11167
* Device is held on return. */
11268
struct hci_dev *hci_dev_get(int index)
@@ -735,6 +691,7 @@ int hci_dev_cmd(unsigned int cmd, void __user *arg)
735691
{
736692
struct hci_dev *hdev;
737693
struct hci_dev_req dr;
694+
__le16 policy;
738695
int err = 0;
739696

740697
if (copy_from_user(&dr, arg, sizeof(dr)))
@@ -761,8 +718,8 @@ int hci_dev_cmd(unsigned int cmd, void __user *arg)
761718

762719
switch (cmd) {
763720
case HCISETAUTH:
764-
err = hci_req_sync(hdev, hci_auth_req, dr.dev_opt,
765-
HCI_INIT_TIMEOUT, NULL);
721+
err = __hci_cmd_sync_status(hdev, HCI_OP_WRITE_AUTH_ENABLE,
722+
1, &dr.dev_opt, HCI_CMD_TIMEOUT);
766723
break;
767724

768725
case HCISETENCRYPT:
@@ -773,19 +730,23 @@ int hci_dev_cmd(unsigned int cmd, void __user *arg)
773730

774731
if (!test_bit(HCI_AUTH, &hdev->flags)) {
775732
/* Auth must be enabled first */
776-
err = hci_req_sync(hdev, hci_auth_req, dr.dev_opt,
777-
HCI_INIT_TIMEOUT, NULL);
733+
err = __hci_cmd_sync_status(hdev,
734+
HCI_OP_WRITE_AUTH_ENABLE,
735+
1, &dr.dev_opt,
736+
HCI_CMD_TIMEOUT);
778737
if (err)
779738
break;
780739
}
781740

782-
err = hci_req_sync(hdev, hci_encrypt_req, dr.dev_opt,
783-
HCI_INIT_TIMEOUT, NULL);
741+
err = __hci_cmd_sync_status(hdev, HCI_OP_WRITE_ENCRYPT_MODE,
742+
1, &dr.dev_opt,
743+
HCI_CMD_TIMEOUT);
784744
break;
785745

786746
case HCISETSCAN:
787-
err = hci_req_sync(hdev, hci_scan_req, dr.dev_opt,
788-
HCI_INIT_TIMEOUT, NULL);
747+
err = __hci_cmd_sync_status(hdev, HCI_OP_WRITE_SCAN_ENABLE,
748+
1, &dr.dev_opt,
749+
HCI_CMD_TIMEOUT);
789750

790751
/* Ensure that the connectable and discoverable states
791752
* get correctly modified as this was a non-mgmt change.
@@ -795,8 +756,11 @@ int hci_dev_cmd(unsigned int cmd, void __user *arg)
795756
break;
796757

797758
case HCISETLINKPOL:
798-
err = hci_req_sync(hdev, hci_linkpol_req, dr.dev_opt,
799-
HCI_INIT_TIMEOUT, NULL);
759+
policy = cpu_to_le16(dr.dev_opt);
760+
761+
err = __hci_cmd_sync_status(hdev, HCI_OP_WRITE_DEF_LINK_POLICY,
762+
2, &policy,
763+
HCI_CMD_TIMEOUT);
800764
break;
801765

802766
case HCISETLINKMODE:

‎net/bluetooth/hci_sync.c‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -280,6 +280,19 @@ int __hci_cmd_sync_status(struct hci_dev *hdev, u16 opcode, u32 plen,
280280
}
281281
EXPORT_SYMBOL(__hci_cmd_sync_status);
282282

283+
int hci_cmd_sync_status(struct hci_dev *hdev, u16 opcode, u32 plen,
284+
const void *param, u32 timeout)
285+
{
286+
int err;
287+
288+
hci_req_sync_lock(hdev);
289+
err = __hci_cmd_sync_status(hdev, opcode, plen, param, timeout);
290+
hci_req_sync_unlock(hdev);
291+
292+
return err;
293+
}
294+
EXPORT_SYMBOL(hci_cmd_sync_status);
295+
283296
static void hci_cmd_sync_work(struct work_struct *work)
284297
{
285298
struct hci_dev *hdev = container_of(work, struct hci_dev, cmd_sync_work);

‎net/bluetooth/l2cap_core.c‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6761,6 +6761,8 @@ static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm,
67616761

67626762
BT_DBG("chan %p, len %d", chan, skb->len);
67636763

6764+
l2cap_chan_lock(chan);
6765+
67646766
if (chan->state != BT_BOUND && chan->state != BT_CONNECTED)
67656767
goto drop;
67666768

@@ -6777,6 +6779,7 @@ static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm,
67776779
}
67786780

67796781
drop:
6782+
l2cap_chan_unlock(chan);
67806783
l2cap_chan_put(chan);
67816784
free_skb:
67826785
kfree_skb(skb);

‎net/bluetooth/l2cap_sock.c‎

Lines changed: 1 addition & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -1489,18 +1489,9 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
14891489
struct l2cap_pinfo *pi;
14901490
int err;
14911491

1492-
/* To avoid race with sock_release, a chan lock needs to be added here
1493-
* to synchronize the sock.
1494-
*/
1495-
l2cap_chan_hold(chan);
1496-
l2cap_chan_lock(chan);
14971492
sk = chan->data;
1498-
1499-
if (!sk) {
1500-
l2cap_chan_unlock(chan);
1501-
l2cap_chan_put(chan);
1493+
if (!sk)
15021494
return -ENXIO;
1503-
}
15041495

15051496
pi = l2cap_pi(sk);
15061497
lock_sock(sk);
@@ -1552,8 +1543,6 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
15521543

15531544
done:
15541545
release_sock(sk);
1555-
l2cap_chan_unlock(chan);
1556-
l2cap_chan_put(chan);
15571546

15581547
return err;
15591548
}

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