Bluetooth: hci_conn, hci_sync: Use __counted_by() to avoid -Wfamnae warnings

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 multiple on-stack definitions
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.

Notice that, due to the use of `__counted_by()` in `struct
hci_cp_le_create_cis`, the for loop in function `hci_cs_le_create_cis()`
had to be modified. Once the index `i`, through which `cp->cis[i]` is
accessed, falls in the interval [0, cp->num_cis), `cp->num_cis` cannot
be decremented all the way down to zero while accessing `cp->cis[]`:

net/bluetooth/hci_event.c:4310:
4310    for (i = 0; cp->num_cis; cp->num_cis--, i++) {
                ...
4314            handle = __le16_to_cpu(cp->cis[i].cis_handle);

otherwise, only half (one iteration before `cp->num_cis == i`) or half
plus one (one iteration before `cp->num_cis < i`) of the items in the
array will be accessed before running into an out-of-bounds issue. So,
in order to avoid this, set `cp->num_cis` to zero just after the for
loop.

Also, make use of `aux_num_cis` variable to update `cmd->num_cis` after
a `list_for_each_entry_rcu()` loop.

With these changes, fix the following warnings:
net/bluetooth/hci_sync.c:1239:56: warning: structure containing a flexible
array member is not at the end of another structure
[-Wflex-array-member-not-at-end]
net/bluetooth/hci_sync.c:1415:51: warning: structure containing a flexible
array member is not at the end of another structure
[-Wflex-array-member-not-at-end]
net/bluetooth/hci_sync.c:1731:51: warning: structure containing a flexible
array member is not at the end of another structure
[-Wflex-array-member-not-at-end]
net/bluetooth/hci_sync.c:6497:45: 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>
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 5c12761cbc0e212e4f7a4c01a60c2bff9bc98027..0b0ac7f065709d99066a03c5843079974906d5db 100644 (file)
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -2026,7 +2026,7 @@ struct hci_cp_le_set_ext_adv_data {
        __u8  operation;
        __u8  frag_pref;
        __u8  length;
-       __u8  data[];
+       __u8  data[] __counted_by(length);
 } __packed;
 
 #define HCI_OP_LE_SET_EXT_SCAN_RSP_DATA                0x2038
@@ -2035,7 +2035,7 @@ struct hci_cp_le_set_ext_scan_rsp_data {
        __u8  operation;
        __u8  frag_pref;
        __u8  length;
-       __u8  data[];
+       __u8  data[] __counted_by(length);
 } __packed;
 
 #define HCI_OP_LE_SET_EXT_ADV_ENABLE           0x2039
@@ -2061,7 +2061,7 @@ struct hci_cp_le_set_per_adv_data {
        __u8  handle;
        __u8  operation;
        __u8  length;
-       __u8  data[];
+       __u8  data[] __counted_by(length);
 } __packed;
 
 #define HCI_OP_LE_SET_PER_ADV_ENABLE           0x2040
@@ -2162,7 +2162,7 @@ struct hci_cis {
 
 struct hci_cp_le_create_cis {
        __u8    num_cis;
-       struct hci_cis cis[];
+       struct hci_cis cis[] __counted_by(num_cis);
 } __packed;
 
 #define HCI_OP_LE_REMOVE_CIG                   0x2065

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index d228321605aee87742109bd9e01c3e71bb32c9c2..122a6a9092e0e10c4b30949f864014bbb5d15084 100644 (file)
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4307,7 +4307,7 @@ static void hci_cs_le_create_cis(struct hci_dev *hdev, u8 status)
        hci_dev_lock(hdev);
 
        /* Remove connection if command failed */
-       for (i = 0; cp->num_cis; cp->num_cis--, i++) {
+       for (i = 0; i < cp->num_cis; i++) {
                struct hci_conn *conn;
                u16 handle;
 
@@ -4323,6 +4323,7 @@ static void hci_cs_le_create_cis(struct hci_dev *hdev, u8 status)
                        hci_conn_del(conn);
                }
        }
+       cp->num_cis = 0;
 
        if (pending)
                hci_le_create_cis_pending(hdev);

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 4c707eb64e6f63d8e2ea85a7ac12a31060dcf7e4..406e36cacd79dbf4229aa39c4c16d90f222b10a3 100644 (file)
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -1235,31 +1235,27 @@ int hci_setup_ext_adv_instance_sync(struct hci_dev *hdev, u8 instance)
 
 static int hci_set_ext_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
 {
-       struct {
-               struct hci_cp_le_set_ext_scan_rsp_data cp;
-               u8 data[HCI_MAX_EXT_AD_LENGTH];
-       } pdu;
+       DEFINE_FLEX(struct hci_cp_le_set_ext_scan_rsp_data, pdu, data, length,
+                   HCI_MAX_EXT_AD_LENGTH);
        u8 len;
        struct adv_info *adv = NULL;
        int err;
 
-       memset(&pdu, 0, sizeof(pdu));
-
        if (instance) {
                adv = hci_find_adv_instance(hdev, instance);
                if (!adv || !adv->scan_rsp_changed)
                        return 0;
        }
 
-       len = eir_create_scan_rsp(hdev, instance, pdu.data);
+       len = eir_create_scan_rsp(hdev, instance, pdu->data);
 
-       pdu.cp.handle = instance;
-       pdu.cp.length = len;
-       pdu.cp.operation = LE_SET_ADV_DATA_OP_COMPLETE;
-       pdu.cp.frag_pref = LE_SET_ADV_DATA_NO_FRAG;
+       pdu->handle = instance;
+       pdu->length = len;
+       pdu->operation = LE_SET_ADV_DATA_OP_COMPLETE;
+       pdu->frag_pref = LE_SET_ADV_DATA_NO_FRAG;
 
        err = __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_EXT_SCAN_RSP_DATA,
-                                   sizeof(pdu.cp) + len, &pdu.cp,
+                                   struct_size(pdu, data, len), pdu,
                                    HCI_CMD_TIMEOUT);
        if (err)
                return err;
@@ -1267,7 +1263,7 @@ static int hci_set_ext_scan_rsp_data_sync(struct hci_dev *hdev, u8 instance)
        if (adv) {
                adv->scan_rsp_changed = false;
        } else {
-               memcpy(hdev->scan_rsp_data, pdu.data, len);
+               memcpy(hdev->scan_rsp_data, pdu->data, len);
                hdev->scan_rsp_data_len = len;
        }
 
@@ -1411,14 +1407,10 @@ static int hci_set_per_adv_params_sync(struct hci_dev *hdev, u8 instance,
 
 static int hci_set_per_adv_data_sync(struct hci_dev *hdev, u8 instance)
 {
-       struct {
-               struct hci_cp_le_set_per_adv_data cp;
-               u8 data[HCI_MAX_PER_AD_LENGTH];
-       } pdu;
+       DEFINE_FLEX(struct hci_cp_le_set_per_adv_data, pdu, data, length,
+                   HCI_MAX_PER_AD_LENGTH);
        u8 len;
 
-       memset(&pdu, 0, sizeof(pdu));
-
        if (instance) {
                struct adv_info *adv = hci_find_adv_instance(hdev, instance);
 
@@ -1426,14 +1418,14 @@ static int hci_set_per_adv_data_sync(struct hci_dev *hdev, u8 instance)
                        return 0;
        }
 
-       len = eir_create_per_adv_data(hdev, instance, pdu.data);
+       len = eir_create_per_adv_data(hdev, instance, pdu->data);
 
-       pdu.cp.length = len;
-       pdu.cp.handle = instance;
-       pdu.cp.operation = LE_SET_ADV_DATA_OP_COMPLETE;
+       pdu->length = len;
+       pdu->handle = instance;
+       pdu->operation = LE_SET_ADV_DATA_OP_COMPLETE;
 
        return __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_PER_ADV_DATA,
-                                    sizeof(pdu.cp) + len, &pdu,
+                                    struct_size(pdu, data, len), pdu,
                                     HCI_CMD_TIMEOUT);
 }
 
@@ -1727,31 +1719,27 @@ int hci_le_terminate_big_sync(struct hci_dev *hdev, u8 handle, u8 reason)
 
 static int hci_set_ext_adv_data_sync(struct hci_dev *hdev, u8 instance)
 {
-       struct {
-               struct hci_cp_le_set_ext_adv_data cp;
-               u8 data[HCI_MAX_EXT_AD_LENGTH];
-       } pdu;
+       DEFINE_FLEX(struct hci_cp_le_set_ext_adv_data, pdu, data, length,
+                   HCI_MAX_EXT_AD_LENGTH);
        u8 len;
        struct adv_info *adv = NULL;
        int err;
 
-       memset(&pdu, 0, sizeof(pdu));
-
        if (instance) {
                adv = hci_find_adv_instance(hdev, instance);
                if (!adv || !adv->adv_data_changed)
                        return 0;
        }
 
-       len = eir_create_adv_data(hdev, instance, pdu.data);
+       len = eir_create_adv_data(hdev, instance, pdu->data);
 
-       pdu.cp.length = len;
-       pdu.cp.handle = instance;
-       pdu.cp.operation = LE_SET_ADV_DATA_OP_COMPLETE;
-       pdu.cp.frag_pref = LE_SET_ADV_DATA_NO_FRAG;
+       pdu->length = len;
+       pdu->handle = instance;
+       pdu->operation = LE_SET_ADV_DATA_OP_COMPLETE;
+       pdu->frag_pref = LE_SET_ADV_DATA_NO_FRAG;
 
        err = __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_EXT_ADV_DATA,
-                                   sizeof(pdu.cp) + len, &pdu.cp,
+                                   struct_size(pdu, data, len), pdu,
                                    HCI_CMD_TIMEOUT);
        if (err)
                return err;
@@ -1760,7 +1748,7 @@ static int hci_set_ext_adv_data_sync(struct hci_dev *hdev, u8 instance)
        if (adv) {
                adv->adv_data_changed = false;
        } else {
-               memcpy(hdev->adv_data, pdu.data, len);
+               memcpy(hdev->adv_data, pdu->data, len);
                hdev->adv_data_len = len;
        }
 
@@ -6493,10 +6481,8 @@ done:
 
 int hci_le_create_cis_sync(struct hci_dev *hdev)
 {
-       struct {
-               struct hci_cp_le_create_cis cp;
-               struct hci_cis cis[0x1f];
-       } cmd;
+       DEFINE_FLEX(struct hci_cp_le_create_cis, cmd, cis, num_cis, 0x1f);
+       size_t aux_num_cis = 0;
        struct hci_conn *conn;
        u8 cig = BT_ISO_QOS_CIG_UNSET;
 
@@ -6523,8 +6509,6 @@ int hci_le_create_cis_sync(struct hci_dev *hdev)
         * remains pending.
         */
 
-       memset(&cmd, 0, sizeof(cmd));
-
        hci_dev_lock(hdev);
 
        rcu_read_lock();
@@ -6561,7 +6545,7 @@ int hci_le_create_cis_sync(struct hci_dev *hdev)
                goto done;
 
        list_for_each_entry_rcu(conn, &hdev->conn_hash.list, list) {
-               struct hci_cis *cis = &cmd.cis[cmd.cp.num_cis];
+               struct hci_cis *cis = &cmd->cis[aux_num_cis];
 
                if (hci_conn_check_create_cis(conn) ||
                    conn->iso_qos.ucast.cig != cig)
@@ -6570,25 +6554,25 @@ int hci_le_create_cis_sync(struct hci_dev *hdev)
                set_bit(HCI_CONN_CREATE_CIS, &conn->flags);
                cis->acl_handle = cpu_to_le16(conn->parent->handle);
                cis->cis_handle = cpu_to_le16(conn->handle);
-               cmd.cp.num_cis++;
+               aux_num_cis++;
 
-               if (cmd.cp.num_cis >= ARRAY_SIZE(cmd.cis))
+               if (aux_num_cis >= 0x1f)
                        break;
        }
+       cmd->num_cis = aux_num_cis;
 
 done:
        rcu_read_unlock();
 
        hci_dev_unlock(hdev);
 
-       if (!cmd.cp.num_cis)
+       if (!aux_num_cis)
                return 0;
 
        /* Wait for HCI_LE_CIS_Established */
        return __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_CREATE_CIS,
-                                       sizeof(cmd.cp) + sizeof(cmd.cis[0]) *
-                                       cmd.cp.num_cis, &cmd,
-                                       HCI_EVT_LE_CIS_ESTABLISHED,
+                                       struct_size(cmd, cis, cmd->num_cis),
+                                       cmd, HCI_EVT_LE_CIS_ESTABLISHED,
                                        conn->conn_timeout, NULL);
 }