[PATCH][next] Bluetooth: hci_conn: Use __counted_by() and avoid -Wfamnae warning

Gustavo A. R. Silva
2024-05-02T16:22:03Z

Prepare for the coming implementation by GCC and Clang of the
__counted_by attribute. Flexible array members annotated with
__counted_by can have their accesses bounds-checked at run-time
via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE
(for strcpy/memcpy-family functions).

Also, -Wflex-array-member-not-at-end is coming in GCC-14, and we are
getting ready to enable it globally.

So, use the `DEFINE_FLEX()` helper for an on-stack definition of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.

With these changes, fix the following warning:
net/bluetooth/hci_conn.c:669:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Link: https://github.com/KSPP/linux/issues/202
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
include/net/bluetooth/hci.h | 2 +-
net/bluetooth/hci_conn.c | 38 ++++++++++++++++---------------------
2 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index c4c6b8810701..e6838321f4d9 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -2144,7 +2144,7 @@ struct hci_cp_le_set_cig_params {
__le16 c_latency;
__le16 p_latency;
__u8 num_cis;
- struct hci_cis_params cis[];
+ struct hci_cis_params cis[] __counted_by(num_cis);
} __packed;

struct hci_rp_le_set_cig_params {
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index c508609be105..6e60e8287956 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -665,11 +665,6 @@ static void le_conn_timeout(struct work_struct *work)
hci_abort_conn(conn, HCI_ERROR_REMOTE_USER_TERM);
}

-struct iso_cig_params {
- struct hci_cp_le_set_cig_params cp;
- struct hci_cis_params cis[0x1f];
-};
-
struct iso_list_data {
union {
u8 cig;
@@ -1725,34 +1720,33 @@ static int hci_le_create_big(struct hci_conn *conn, struct bt_iso_qos *qos)

static int set_cig_params_sync(struct hci_dev *hdev, void *data)
{
+ DEFINE_FLEX(struct hci_cp_le_set_cig_params, pdu, cis, num_cis, 0x1f);
u8 cig_id = PTR_UINT(data);
struct hci_conn *conn;
struct bt_iso_qos *qos;
- struct iso_cig_params pdu;
+ u8 aux_num_cis = 0;
u8 cis_id;

conn = hci_conn_hash_lookup_cig(hdev, cig_id);
if (!conn)
return 0;

- memset(&pdu, 0, sizeof(pdu));
-
qos = &conn->iso_qos;
- pdu.cp.cig_id = cig_id;
- hci_cpu_to_le24(qos->ucast.out.interval, pdu.cp.c_interval);
- hci_cpu_to_le24(qos->ucast.in.interval, pdu.cp.p_interval);
- pdu.cp.sca = qos->ucast.sca;
- pdu.cp.packing = qos->ucast.packing;
- pdu.cp.framing = qos->ucast.framing;
- pdu.cp.c_latency = cpu_to_le16(qos->ucast.out.latency);
- pdu.cp.p_latency = cpu_to_le16(qos->ucast.in.latency);
+ pdu->cig_id = cig_id;
+ hci_cpu_to_le24(qos->ucast.out.interval, pdu->c_interval);
+ hci_cpu_to_le24(qos->ucast.in.interval, pdu->p_interval);
+ pdu->sca = qos->ucast.sca;
+ pdu->packing = qos->ucast.packing;
+ pdu->framing = qos->ucast.framing;
+ pdu->c_latency = cpu_to_le16(qos->ucast.out.latency);
+ pdu->p_latency = cpu_to_le16(qos->ucast.in.latency);

/* Reprogram all CIS(s) with the same CIG, valid range are:
* num_cis: 0x00 to 0x1F
* cis_id: 0x00 to 0xEF
*/
for (cis_id = 0x00; cis_id < 0xf0 &&
- pdu.cp.num_cis < ARRAY_SIZE(pdu.cis); cis_id++) {
+ aux_num_cis < pdu->num_cis; cis_id++) {
struct hci_cis_params *cis;

conn = hci_conn_hash_lookup_cis(hdev, NULL, 0, cig_id, cis_id);
@@ -1761,7 +1755,7 @@ static int set_cig_params_sync(struct hci_dev *hdev, void *data)

qos = &conn->iso_qos;

- cis = &pdu.cis[pdu.cp.num_cis++];
+ cis = &pdu->cis[aux_num_cis++];
cis->cis_id = cis_id;
cis->c_sdu = cpu_to_le16(conn->iso_qos.ucast.out.sdu);
cis->p_sdu = cpu_to_le16(conn->iso_qos.ucast.in.sdu);
@@ -1772,14 +1766,14 @@ static int set_cig_params_sync(struct hci_dev *hdev, void *data)
cis->c_rtn = qos->ucast.out.rtn;
cis->p_rtn = qos->ucast.in.rtn;
}
+ pdu->num_cis = aux_num_cis;

- if (!pdu.cp.num_cis)
+ if (!pdu->num_cis)
return 0;

return __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_CIG_PARAMS,
- sizeof(pdu.cp) +
- pdu.cp.num_cis * sizeof(pdu.cis[0]), &pdu,
- HCI_CMD_TIMEOUT);
+ struct_size(pdu, cis, pdu->num_cis),
+ pdu, HCI_CMD_TIMEOUT);
}

static bool hci_le_set_cig_params(struct hci_conn *conn, struct bt_iso_qos *qos)
--
2.34.1