[PATCH 6.19 135/342] Bluetooth: L2CAP: Fix not tracking outstanding TX ident

Greg Kroah-Hartman
2026-03-31T16:37:03Z

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

[ Upstream commit 6c3ea155e5ee3e56606233acde8309afda66d483 ]

This attempts to proper track outstanding request by using struct ida
and allocating from it in l2cap_get_ident using ida_alloc_range which
would reuse ids as they are free, then upon completion release
the id using ida_free.

This fixes the qualification test case L2CAP/COS/CED/BI-29-C which
attempts to check if the host stack is able to work after 256 attempts
to connect which requires Ident field to use the full range of possible
values in order to pass the test.

Link: https://github.com/bluez/bluez/issues/1829
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Stable-dep-of: 00fdebbbc557 ("Bluetooth: L2CAP: Fix deadlock in l2cap_conn_del()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/bluetooth/l2cap.h | 3 +--
net/bluetooth/l2cap_core.c | 46 ++++++++++++++++++++++++-----------
2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index f08ed93bb6fa3..010f1a8fd15f8 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -657,8 +657,7 @@ struct l2cap_conn {

struct sk_buff *rx_skb;
__u32 rx_len;
- __u8 tx_ident;
- struct mutex ident_lock;
+ struct ida tx_ida;

struct sk_buff_head pending_rx;
struct work_struct pending_rx_work;
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index b5e393e4f3eb1..5bd5561a8dbf5 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -924,26 +924,18 @@ int l2cap_chan_check_security(struct l2cap_chan *chan, bool initiator)
initiator);
}

-static u8 l2cap_get_ident(struct l2cap_conn *conn)
+static int l2cap_get_ident(struct l2cap_conn *conn)
{
- u8 id;
+ /* LE link does not support tools like l2ping so use the full range */
+ if (conn->hcon->type == LE_LINK)
+ return ida_alloc_range(&conn->tx_ida, 1, 255, GFP_ATOMIC);

/* Get next available identificator.
* 1 - 128 are used by kernel.
* 129 - 199 are reserved.
* 200 - 254 are used by utilities like l2ping, etc.
*/
-
- mutex_lock(&conn->ident_lock);
-
- if (++conn->tx_ident > 128)
- conn->tx_ident = 1;
-
- id = conn->tx_ident;
-
- mutex_unlock(&conn->ident_lock);
-
- return id;
+ return ida_alloc_range(&conn->tx_ida, 1, 128, GFP_ATOMIC);
}

static void l2cap_send_acl(struct l2cap_conn *conn, struct sk_buff *skb,
@@ -1769,6 +1761,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
if (work_pending(&conn->pending_rx_work))
cancel_work_sync(&conn->pending_rx_work);

+ ida_destroy(&conn->tx_ida);
+
cancel_delayed_work_sync(&conn->id_addr_timer);

l2cap_unregister_all_users(conn);
@@ -4780,12 +4774,34 @@ static int l2cap_le_connect_rsp(struct l2cap_conn *conn,
return err;
}

+static void l2cap_put_ident(struct l2cap_conn *conn, u8 code, u8 id)
+{
+ switch (code) {
+ case L2CAP_COMMAND_REJ:
+ case L2CAP_CONN_RSP:
+ case L2CAP_CONF_RSP:
+ case L2CAP_DISCONN_RSP:
+ case L2CAP_ECHO_RSP:
+ case L2CAP_INFO_RSP:
+ case L2CAP_CONN_PARAM_UPDATE_RSP:
+ case L2CAP_ECRED_CONN_RSP:
+ case L2CAP_ECRED_RECONF_RSP:
+ /* First do a lookup since the remote may send bogus ids that
+ * would make ida_free to generate warnings.
+ */
+ if (ida_find_first_range(&conn->tx_ida, id, id) >= 0)
+ ida_free(&conn->tx_ida, id);
+ }
+}
+
static inline int l2cap_bredr_sig_cmd(struct l2cap_conn *conn,
struct l2cap_cmd_hdr *cmd, u16 cmd_len,
u8 *data)
{
int err = 0;

+ l2cap_put_ident(conn, cmd->code, cmd->ident);
+
switch (cmd->code) {
case L2CAP_COMMAND_REJ:
l2cap_command_rej(conn, cmd, cmd_len, data);
@@ -5470,6 +5486,8 @@ static inline int l2cap_le_sig_cmd(struct l2cap_conn *conn,
{
int err = 0;

+ l2cap_put_ident(conn, cmd->code, cmd->ident);
+
switch (cmd->code) {
case L2CAP_COMMAND_REJ:
l2cap_le_command_rej(conn, cmd, cmd_len, data);
@@ -6972,13 +6990,13 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon)
hci_dev_test_flag(hcon->hdev, HCI_FORCE_BREDR_SMP)))
conn->local_fixed_chan |= L2CAP_FC_SMP_BREDR;

- mutex_init(&conn->ident_lock);
mutex_init(&conn->lock);

INIT_LIST_HEAD(&conn->chan_l);
INIT_LIST_HEAD(&conn->users);

INIT_DELAYED_WORK(&conn->info_timer, l2cap_info_timeout);
+ ida_init(&conn->tx_ida);

skb_queue_head_init(&conn->pending_rx);
INIT_WORK(&conn->pending_rx_work, process_pending_rx);
--
2.51.0