Bluetooth: hci_conn: Use __counted_by() to avoid -Wfamnae warning

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 <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 0b0ac7f065709d99066a03c5843079974906d5db..c4c6b881070100cddeddd78cfaabf34d55cd8a59 100644 (file)
--- 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 c1d6b4d713b40f07c8ec91e540adb750769f5413..8375f7bd58ee0ce41f7ab1b12f2fd68bcad51455 100644 (file)
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2109,13 +2109,10 @@ 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);
@@ -2125,18 +2122,17 @@ 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)