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:2116:50: 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 <gustavo...@kernel.org> --- Changes in v2: - Use `sizeof(*pdu) + num_bis` instead of `__struct_size(pdu)` v1: - Link: https://lore.kernel.org/linux-hardening/ZivYcpzZsc7aIFZ5@neat/ include/net/bluetooth/hci.h | 2 +- net/bluetooth/hci_conn.c | 26 +++++++++++--------------- 2 files changed, 12 insertions(+), 16 deletions(-) diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h index 5c12761cbc0e..fe23e862921d 100644 --- a/include/net/bluetooth/hci.h +++ b/include/net/bluetooth/hci.h @@ -2216,7 +2216,7 @@ struct hci_cp_le_big_create_sync { __u8 mse; __le16 timeout; __u8 num_bis; - __u8 bis[]; + __u8 bis[] __counted_by(num_bis); } __packed; #define HCI_OP_LE_BIG_TERM_SYNC 0x206c diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c index 81166a5bc034..d6daf55f0307 100644 --- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -2112,13 +2112,10 @@ int hci_le_big_create_sync(struct hci_dev *hdev, struct hci_conn *hcon, struct bt_iso_qos *qos, __u16 sync_handle, __u8 num_bis, __u8 bis[]) { - struct _packed { - struct hci_cp_le_big_create_sync cp; - __u8 bis[0x11]; - } pdu; + DEFINE_FLEX(struct hci_cp_le_big_create_sync, pdu, bis, num_bis, 0x11); int err; - if (num_bis < 0x01 || num_bis > sizeof(pdu.bis)) + if (num_bis < 0x01 || num_bis > pdu->num_bis) return -EINVAL; err = qos_set_big(hdev, qos); @@ -2128,18 +2125,17 @@ int hci_le_big_create_sync(struct hci_dev *hdev, struct hci_conn *hcon, if (hcon) hcon->iso_qos.bcast.big = qos->bcast.big; - memset(&pdu, 0, sizeof(pdu)); - pdu.cp.handle = qos->bcast.big; - pdu.cp.sync_handle = cpu_to_le16(sync_handle); - pdu.cp.encryption = qos->bcast.encryption; - memcpy(pdu.cp.bcode, qos->bcast.bcode, sizeof(pdu.cp.bcode)); - pdu.cp.mse = qos->bcast.mse; - pdu.cp.timeout = cpu_to_le16(qos->bcast.timeout); - pdu.cp.num_bis = num_bis; - memcpy(pdu.bis, bis, num_bis); + pdu->handle = qos->bcast.big; + pdu->sync_handle = cpu_to_le16(sync_handle); + pdu->encryption = qos->bcast.encryption; + memcpy(pdu->bcode, qos->bcast.bcode, sizeof(pdu->bcode)); + pdu->mse = qos->bcast.mse; + pdu->timeout = cpu_to_le16(qos->bcast.timeout); + pdu->num_bis = num_bis; + memcpy(pdu->bis, bis, num_bis); return hci_send_cmd(hdev, HCI_OP_LE_BIG_CREATE_SYNC, - sizeof(pdu.cp) + num_bis, &pdu); + sizeof(*pdu) + num_bis, pdu); } static void create_big_complete(struct hci_dev *hdev, void *data, int err) -- 2.34.1
