[PATCH 6.6 082/102] Bluetooth: L2CAP: Fix div-by-zero in l2cap_le_flowctl_init()

Greg Kroah-Hartman
2024-05-23T13:27:32Z

From: Sungwoo Kim <iam@sung-woo.kim>

commit a5b862c6a221459d54e494e88965b48dcfa6cc44 upstream.

l2cap_le_flowctl_init() can cause both div-by-zero and an integer
overflow since hdev->le_mtu may not fall in the valid range.

Move MTU from hci_dev to hci_conn to validate MTU and stop the connection
process earlier if MTU is invalid.
Also, add a missing validation in read_buffer_size() and make it return
an error value if the validation fails.
Now hci_conn_add() returns ERR_PTR() as it can fail due to the both a
kzalloc failure and invalid MTU value.

divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 PID: 67 Comm: kworker/u5:0 Tainted: G W 6.9.0-rc5+ #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: hci0 hci_rx_work
RIP: 0010:l2cap_le_flowctl_init+0x19e/0x3f0 net/bluetooth/l2cap_core.c:547
Code: e8 17 17 0c 00 66 41 89 9f 84 00 00 00 bf 01 00 00 00 41 b8 02 00 00 00 4c
89 fe 4c 89 e2 89 d9 e8 27 17 0c 00 44 89 f0 31 d2 <66> f7 f3 89 c3 ff c3 4d 8d
b7 88 00 00 00 4c 89 f0 48 c1 e8 03 42
RSP: 0018:ffff88810bc0f858 EFLAGS: 00010246
RAX: 00000000000002a0 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: ffff88810bc0f7c0 RDI: ffffc90002dcb66f
RBP: ffff88810bc0f880 R08: aa69db2dda70ff01 R09: 0000ffaaaaaaaaaa
R10: 0084000000ffaaaa R11: 0000000000000000 R12: ffff88810d65a084
R13: dffffc0000000000 R14: 00000000000002a0 R15: ffff88810d65a000
FS: 0000000000000000(0000) GS:ffff88811ac00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000100 CR3: 0000000103268003 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
l2cap_le_connect_req net/bluetooth/l2cap_core.c:4902 [inline]
l2cap_le_sig_cmd net/bluetooth/l2cap_core.c:5420 [inline]
l2cap_le_sig_channel net/bluetooth/l2cap_core.c:5486 [inline]
l2cap_recv_frame+0xe59d/0x11710 net/bluetooth/l2cap_core.c:6809
l2cap_recv_acldata+0x544/0x10a0 net/bluetooth/l2cap_core.c:7506
hci_acldata_packet net/bluetooth/hci_core.c:3939 [inline]
hci_rx_work+0x5e5/0xb20 net/bluetooth/hci_core.c:4176
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0x90f/0x1530 kernel/workqueue.c:3335
worker_thread+0x926/0xe70 kernel/workqueue.c:3416
kthread+0x2e3/0x380 kernel/kthread.c:388
ret_from_fork+0x5c/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---

Fixes: 6ed58ec520ad ("Bluetooth: Use LE buffers for LE traffic")
Suggested-by: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/bluetooth/hci.h | 9 ++++
include/net/bluetooth/hci_core.h | 1
net/bluetooth/hci_conn.c | 71 ++++++++++++++++++++++++++-------------
net/bluetooth/hci_event.c | 31 ++++++++++-------
net/bluetooth/iso.c | 2 -
net/bluetooth/l2cap_core.c | 17 +--------
net/bluetooth/sco.c | 6 +--
7 files changed, 86 insertions(+), 51 deletions(-)

--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -1662,6 +1662,15 @@ struct hci_cp_le_set_event_mask {
__u8 mask[8];
} __packed;

+/* BLUETOOTH CORE SPECIFICATION Version 5.4 | Vol 4, Part E
+ * 7.8.2 LE Read Buffer Size command
+ * MAX_LE_MTU is 0xffff.
+ * 0 is also valid. It means that no dedicated LE Buffer exists.
+ * It should use the HCI_Read_Buffer_Size command and mtu is shared
+ * between BR/EDR and LE.
+ */
+#define HCI_MIN_LE_MTU 0x001b
+
#define HCI_OP_LE_READ_BUFFER_SIZE 0x2002
struct hci_rp_le_read_buffer_size {
__u8 status;
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -707,6 +707,7 @@ struct hci_conn {
__u16 handle;
__u16 sync_handle;
__u16 state;
+ __u16 mtu;
__u8 mode;
__u8 type;
__u8 role;
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -939,11 +939,37 @@ struct hci_conn *hci_conn_add(struct hci
{
struct hci_conn *conn;

+ switch (type) {
+ case ACL_LINK:
+ if (!hdev->acl_mtu)
+ return ERR_PTR(-ECONNREFUSED);
+ break;
+ case ISO_LINK:
+ if (hdev->iso_mtu)
+ /* Dedicated ISO Buffer exists */
+ break;
+ fallthrough;
+ case LE_LINK:
+ if (hdev->le_mtu && hdev->le_mtu < HCI_MIN_LE_MTU)
+ return ERR_PTR(-ECONNREFUSED);
+ if (!hdev->le_mtu && hdev->acl_mtu < HCI_MIN_LE_MTU)
+ return ERR_PTR(-ECONNREFUSED);
+ break;
+ case SCO_LINK:
+ case ESCO_LINK:
+ if (!hdev->sco_pkts)
+ /* Controller does not support SCO or eSCO over HCI */
+ return ERR_PTR(-ECONNREFUSED);
+ break;
+ default:
+ return ERR_PTR(-ECONNREFUSED);
+ }
+
bt_dev_dbg(hdev, "dst %pMR handle 0x%4.4x", dst, handle);

conn = kzalloc(sizeof(*conn), GFP_KERNEL);
if (!conn)
- return NULL;
+ return ERR_PTR(-ENOMEM);

bacpy(&conn->dst, dst);
bacpy(&conn->src, &hdev->bdaddr);
@@ -974,10 +1000,12 @@ struct hci_conn *hci_conn_add(struct hci
switch (type) {
case ACL_LINK:
conn->pkt_type = hdev->pkt_type & ACL_PTYPE_MASK;
+ conn->mtu = hdev->acl_mtu;
break;
case LE_LINK:
/* conn->src should reflect the local identity address */
hci_copy_identity_address(hdev, &conn->src, &conn->src_type);
+ conn->mtu = hdev->le_mtu ? hdev->le_mtu : hdev->acl_mtu;
break;
case ISO_LINK:
/* conn->src should reflect the local identity address */
@@ -989,6 +1017,8 @@ struct hci_conn *hci_conn_add(struct hci
else if (conn->role == HCI_ROLE_MASTER)
conn->cleanup = cis_cleanup;

+ conn->mtu = hdev->iso_mtu ? hdev->iso_mtu :
+ hdev->le_mtu ? hdev->le_mtu : hdev->acl_mtu;
break;
case SCO_LINK:
if (lmp_esco_capable(hdev))
@@ -996,9 +1026,12 @@ struct hci_conn *hci_conn_add(struct hci
(hdev->esco_type & EDR_ESCO_MASK);
else
conn->pkt_type = hdev->pkt_type & SCO_PTYPE_MASK;
+
+ conn->mtu = hdev->sco_mtu;
break;
case ESCO_LINK:
conn->pkt_type = hdev->esco_type & ~EDR_ESCO_MASK;
+ conn->mtu = hdev->sco_mtu;
break;
}

@@ -1041,7 +1074,7 @@ struct hci_conn *hci_conn_add_unset(stru

handle = hci_conn_hash_alloc_unset(hdev);
if (unlikely(handle < 0))
- return NULL;
+ return ERR_PTR(-ECONNREFUSED);

return hci_conn_add(hdev, type, dst, role, handle);
}
@@ -1384,8 +1417,8 @@ struct hci_conn *hci_connect_le(struct h
bacpy(&conn->dst, dst);
} else {
conn = hci_conn_add_unset(hdev, LE_LINK, dst, role);
- if (!conn)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(conn))
+ return conn;
hci_conn_hold(conn);
conn->pending_sec_level = sec_level;
}
@@ -1549,8 +1582,8 @@ static struct hci_conn *hci_add_bis(stru
return ERR_PTR(-EADDRINUSE);

conn = hci_conn_add_unset(hdev, ISO_LINK, dst, HCI_ROLE_MASTER);
- if (!conn)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(conn))
+ return conn;

conn->state = BT_CONNECT;

@@ -1593,8 +1626,8 @@ struct hci_conn *hci_connect_le_scan(str
BT_DBG("requesting refresh of dst_addr");

conn = hci_conn_add_unset(hdev, LE_LINK, dst, HCI_ROLE_MASTER);
- if (!conn)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(conn))
+ return conn;

if (hci_explicit_conn_params_set(hdev, dst, dst_type) < 0) {
hci_conn_del(conn);
@@ -1641,8 +1674,8 @@ struct hci_conn *hci_connect_acl(struct
acl = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst);
if (!acl) {
acl = hci_conn_add_unset(hdev, ACL_LINK, dst, HCI_ROLE_MASTER);
- if (!acl)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(acl))
+ return acl;
}

hci_conn_hold(acl);
@@ -1701,9 +1734,9 @@ struct hci_conn *hci_connect_sco(struct
sco = hci_conn_hash_lookup_ba(hdev, type, dst);
if (!sco) {
sco = hci_conn_add_unset(hdev, type, dst, HCI_ROLE_MASTER);
- if (!sco) {
+ if (IS_ERR(sco)) {
hci_conn_drop(acl);
- return ERR_PTR(-ENOMEM);
+ return sco;
}
}

@@ -1893,8 +1926,8 @@ struct hci_conn *hci_bind_cis(struct hci
qos->ucast.cis);
if (!cis) {
cis = hci_conn_add_unset(hdev, ISO_LINK, dst, HCI_ROLE_MASTER);
- if (!cis)
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(cis))
+ return cis;
cis->cleanup = cis_cleanup;
cis->dst_type = dst_type;
cis->iso_qos.ucast.cig = BT_ISO_QOS_CIG_UNSET;
@@ -2029,14 +2062,8 @@ static void hci_iso_qos_setup(struct hci
struct bt_iso_io_qos *qos, __u8 phy)
{
/* Only set MTU if PHY is enabled */
- if (!qos->sdu && qos->phy) {
- if (hdev->iso_mtu > 0)
- qos->sdu = hdev->iso_mtu;
- else if (hdev->le_mtu > 0)
- qos->sdu = hdev->le_mtu;
- else
- qos->sdu = hdev->acl_mtu;
- }
+ if (!qos->sdu && qos->phy)
+ qos->sdu = conn->mtu;

/* Use the same PHY as ACL if set to any */
if (qos->phy == BT_ISO_PHY_ANY)
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -958,6 +958,9 @@ static u8 hci_cc_read_buffer_size(struct
BT_DBG("%s acl mtu %d:%d sco mtu %d:%d", hdev->name, hdev->acl_mtu,
hdev->acl_pkts, hdev->sco_mtu, hdev->sco_pkts);

+ if (!hdev->acl_mtu || !hdev->acl_pkts)
+ return HCI_ERROR_INVALID_PARAMETERS;
+
return rp->status;
}

@@ -1267,6 +1270,9 @@ static u8 hci_cc_le_read_buffer_size(str

BT_DBG("%s le mtu %d:%d", hdev->name, hdev->le_mtu, hdev->le_pkts);

+ if (hdev->le_mtu && hdev->le_mtu < HCI_MIN_LE_MTU)
+ return HCI_ERROR_INVALID_PARAMETERS;
+
return rp->status;
}

@@ -2351,8 +2357,8 @@ static void hci_cs_create_conn(struct hc
if (!conn) {
conn = hci_conn_add_unset(hdev, ACL_LINK, &cp->bdaddr,
HCI_ROLE_MASTER);
- if (!conn)
- bt_dev_err(hdev, "no memory for new connection");
+ if (IS_ERR(conn))
+ bt_dev_err(hdev, "connection err: %ld", PTR_ERR(conn));
}
}

@@ -3165,8 +3171,8 @@ static void hci_conn_complete_evt(struct
BDADDR_BREDR)) {
conn = hci_conn_add_unset(hdev, ev->link_type,
&ev->bdaddr, HCI_ROLE_SLAVE);
- if (!conn) {
- bt_dev_err(hdev, "no memory for new conn");
+ if (IS_ERR(conn)) {
+ bt_dev_err(hdev, "connection err: %ld", PTR_ERR(conn));
goto unlock;
}
} else {
@@ -3356,8 +3362,8 @@ static void hci_conn_request_evt(struct
if (!conn) {
conn = hci_conn_add_unset(hdev, ev->link_type, &ev->bdaddr,
HCI_ROLE_SLAVE);
- if (!conn) {
- bt_dev_err(hdev, "no memory for new connection");
+ if (IS_ERR(conn)) {
+ bt_dev_err(hdev, "connection err: %ld", PTR_ERR(conn));
goto unlock;
}
}
@@ -3834,6 +3840,9 @@ static u8 hci_cc_le_read_buffer_size_v2(
BT_DBG("%s acl mtu %d:%d iso mtu %d:%d", hdev->name, hdev->acl_mtu,
hdev->acl_pkts, hdev->iso_mtu, hdev->iso_pkts);

+ if (hdev->le_mtu && hdev->le_mtu < HCI_MIN_LE_MTU)
+ return HCI_ERROR_INVALID_PARAMETERS;
+
return rp->status;
}

@@ -5925,8 +5934,8 @@ static void le_conn_complete_evt(struct
goto unlock;

conn = hci_conn_add_unset(hdev, LE_LINK, bdaddr, role);
- if (!conn) {
- bt_dev_err(hdev, "no memory for new connection");
+ if (IS_ERR(conn)) {
+ bt_dev_err(hdev, "connection err: %ld", PTR_ERR(conn));
goto unlock;
}

@@ -7051,7 +7060,7 @@ static void hci_le_cis_req_evt(struct hc
if (!cis) {
cis = hci_conn_add(hdev, ISO_LINK, &acl->dst, HCI_ROLE_SLAVE,
cis_handle);
- if (!cis) {
+ if (IS_ERR(cis)) {
hci_le_reject_cis(hdev, ev->cis_handle);
goto unlock;
}
@@ -7170,7 +7179,7 @@ static void hci_le_big_sync_established_
if (!bis) {
bis = hci_conn_add(hdev, ISO_LINK, BDADDR_ANY,
HCI_ROLE_SLAVE, handle);
- if (!bis)
+ if (IS_ERR(bis))
continue;
}

@@ -7242,7 +7251,7 @@ static void hci_le_big_info_adv_report_e
pa_sync = hci_conn_add_unset(hdev, ISO_LINK, BDADDR_ANY,
HCI_ROLE_SLAVE);

- if (!pa_sync)
+ if (IS_ERR(pa_sync))
goto unlock;

pa_sync->sync_handle = le16_to_cpu(ev->sync_handle);
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1135,7 +1135,7 @@ static int iso_sock_sendmsg(struct socke
return -ENOTCONN;
}

- mtu = iso_pi(sk)->conn->hcon->hdev->iso_mtu;
+ mtu = iso_pi(sk)->conn->hcon->mtu;

release_sock(sk);

--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -6241,7 +6241,7 @@ static int l2cap_finish_move(struct l2ca
BT_DBG("chan %p", chan);

chan->rx_state = L2CAP_RX_STATE_RECV;
- chan->conn->mtu = chan->conn->hcon->hdev->acl_mtu;
+ chan->conn->mtu = chan->conn->hcon->mtu;

return l2cap_resegment(chan);
}
@@ -6308,7 +6308,7 @@ static int l2cap_rx_state_wait_f(struct
*/
chan->next_tx_seq = control->reqseq;
chan->unacked_frames = 0;
- chan->conn->mtu = chan->conn->hcon->hdev->acl_mtu;
+ chan->conn->mtu = chan->conn->hcon->mtu;

err = l2cap_resegment(chan);

@@ -6848,18 +6848,7 @@ static struct l2cap_conn *l2cap_conn_add

BT_DBG("hcon %p conn %p hchan %p", hcon, conn, hchan);

- switch (hcon->type) {
- case LE_LINK:
- if (hcon->hdev->le_mtu) {
- conn->mtu = hcon->hdev->le_mtu;
- break;
- }
- fallthrough;
- default:
- conn->mtu = hcon->hdev->acl_mtu;
- break;
- }
-
+ conn->mtu = hcon->mtu;
conn->feat_mask = 0;

conn->local_fixed_chan = L2CAP_FC_SIG_BREDR | L2CAP_FC_CONNLESS;
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -126,7 +126,6 @@ static void sco_sock_clear_timer(struct
/* ---- SCO connections ---- */
static struct sco_conn *sco_conn_add(struct hci_conn *hcon)
{
- struct hci_dev *hdev = hcon->hdev;
struct sco_conn *conn = hcon->sco_data;

if (conn) {
@@ -144,9 +143,10 @@ static struct sco_conn *sco_conn_add(str

hcon->sco_data = conn;
conn->hcon = hcon;
+ conn->mtu = hcon->mtu;

- if (hdev->sco_mtu > 0)
- conn->mtu = hdev->sco_mtu;
+ if (hcon->mtu > 0)
+ conn->mtu = hcon->mtu;
else
conn->mtu = 60;