wireless: marvell: Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Ganapathi Bhat <ganapathi.bhat@nxp.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200225020413.GA8057@embeddedor

diff --git a/drivers/net/wireless/marvell/libertas_tf/if_usb.h b/drivers/net/wireless/marvell/libertas_tf/if_usb.h
index 585ad36f90551184e3823db89ef0dfbdf9a76d9e..f6dd7373b09e45d01e57d55d90f944a75ab135a6 100644 (file)
--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.h
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.h
@@ -81,7 +81,7 @@ struct fwheader {
 struct fwdata {
        struct fwheader hdr;
        __le32 seqnum;
-       uint8_t data[0];
+       uint8_t data[];
 };
 
 /** fwsyncheader */

diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
index 4dfdf928f7052b68e6aa3e737afdf552db14867d..a415d73a73e620670face4515320bb12ba46eb0b 100644 (file)
--- a/drivers/net/wireless/marvell/mwifiex/fw.h
+++ b/drivers/net/wireless/marvell/mwifiex/fw.h
@@ -846,7 +846,7 @@ struct mwifiex_ie_types_random_mac {
 
 struct mwifiex_ietypes_chanstats {
        struct mwifiex_ie_types_header header;
-       struct mwifiex_fw_chan_stats chanstats[0];
+       struct mwifiex_fw_chan_stats chanstats[];
 } __packed;
 
 struct mwifiex_ie_types_wildcard_ssid_params {
@@ -1082,7 +1082,7 @@ struct host_cmd_ds_get_hw_spec {
        __le32 reserved_6;
        __le32 dot_11ac_dev_cap;
        __le32 dot_11ac_mcs_support;
-       u8 tlvs[0];
+       u8 tlvs[];
 } __packed;
 
 struct host_cmd_ds_802_11_rssi_info {
@@ -1140,7 +1140,7 @@ struct ieee_types_assoc_rsp {
        __le16 cap_info_bitmap;
        __le16 status_code;
        __le16 a_id;
-       u8 ie_buffer[0];
+       u8 ie_buffer[];
 } __packed;
 
 struct host_cmd_ds_802_11_associate_rsp {
@@ -1455,7 +1455,7 @@ struct host_cmd_ds_chan_rpt_event {
        __le32 result;
        __le64 start_tsf;
        __le32 duration;
-       u8 tlvbuf[0];
+       u8 tlvbuf[];
 } __packed;
 
 struct host_cmd_sdio_sp_rx_aggr_cfg {
@@ -1625,7 +1625,7 @@ struct host_cmd_ds_802_11_bg_scan_config {
        __le32 reserved2;
        __le32 report_condition;
        __le16 reserved3;
-       u8 tlv[0];
+       u8 tlv[];
 } __packed;
 
 struct host_cmd_ds_802_11_bg_scan_query {
@@ -1720,7 +1720,7 @@ struct mwifiex_ie_types_sta_info {
 
 struct host_cmd_ds_sta_list {
        __le16 sta_count;
-       u8 tlv[0];
+       u8 tlv[];
 } __packed;
 
 struct mwifiex_ie_types_pwr_capability {
@@ -1743,7 +1743,7 @@ struct mwifiex_ie_types_wmm_param_set {
 struct mwifiex_ie_types_mgmt_frame {
        struct mwifiex_ie_types_header header;
        __le16 frame_control;
-       u8 frame_contents[0];
+       u8 frame_contents[];
 };
 
 struct mwifiex_ie_types_wmm_queue_status {
@@ -1861,7 +1861,7 @@ struct mwifiex_ie_types_2040bssco {
 
 struct mwifiex_ie_types_extcap {
        struct mwifiex_ie_types_header header;
-       u8 ext_capab[0];
+       u8 ext_capab[];
 } __packed;
 
 struct host_cmd_ds_mem_access {
@@ -1918,12 +1918,12 @@ struct mwifiex_assoc_event {
        __le16 frame_control;
        __le16 cap_info;
        __le16 listen_interval;
-       u8 data[0];
+       u8 data[];
 } __packed;
 
 struct host_cmd_ds_sys_config {
        __le16 action;
-       u8 tlv[0];
+       u8 tlv[];
 };
 
 struct host_cmd_11ac_vht_cfg {
@@ -1956,7 +1956,7 @@ struct host_cmd_tlv_gwk_cipher {
 
 struct host_cmd_tlv_passphrase {
        struct mwifiex_ie_types_header header;
-       u8 passphrase[0];
+       u8 passphrase[];
 } __packed;
 
 struct host_cmd_tlv_wep_key {
@@ -1978,12 +1978,12 @@ struct host_cmd_tlv_encrypt_protocol {
 
 struct host_cmd_tlv_ssid {
        struct mwifiex_ie_types_header header;
-       u8 ssid[0];
+       u8 ssid[];
 } __packed;
 
 struct host_cmd_tlv_rates {
        struct mwifiex_ie_types_header header;
-       u8 rates[0];
+       u8 rates[];
 } __packed;
 
 struct mwifiex_ie_types_bssid_list {
@@ -2100,13 +2100,13 @@ struct mwifiex_fw_mef_entry {
        u8 mode;
        u8 action;
        __le16 exprsize;
-       u8 expr[0];
+       u8 expr[];
 } __packed;
 
 struct host_cmd_ds_mef_cfg {
        __le32 criteria;
        __le16 num_entries;
-       struct mwifiex_fw_mef_entry mef_entry[0];
+       struct mwifiex_fw_mef_entry mef_entry[];
 } __packed;
 
 #define CONNECTION_TYPE_INFRA   0
@@ -2169,7 +2169,7 @@ struct mwifiex_radar_det_event {
 struct mwifiex_ie_types_multi_chan_info {
        struct mwifiex_ie_types_header header;
        __le16 status;
-       u8 tlv_buffer[0];
+       u8 tlv_buffer[];
 } __packed;
 
 struct mwifiex_ie_types_mc_group_info {
@@ -2185,7 +2185,7 @@ struct mwifiex_ie_types_mc_group_info {
                u8 usb_ep_num;
        } hid_num;
        u8 intf_num;
-       u8 bss_type_numlist[0];
+       u8 bss_type_numlist[];
 } __packed;
 
 struct meas_rpt_map {
@@ -2250,13 +2250,13 @@ struct coalesce_receive_filt_rule {
        u8 num_of_fields;
        u8 pkt_type;
        __le16 max_coalescing_delay;
-       struct coalesce_filt_field_param params[0];
+       struct coalesce_filt_field_param params[];
 } __packed;
 
 struct host_cmd_ds_coalesce_cfg {
        __le16 action;
        __le16 num_of_rules;
-       struct coalesce_receive_filt_rule rule[0];
+       struct coalesce_receive_filt_rule rule[];
 } __packed;
 
 struct host_cmd_ds_multi_chan_policy {
@@ -2295,7 +2295,7 @@ struct host_cmd_ds_pkt_aggr_ctrl {
 
 struct host_cmd_ds_sta_configure {
        __le16 action;
-       u8 tlv_buffer[0];
+       u8 tlv_buffer[];
 } __packed;
 
 struct host_cmd_ds_command {

diff --git a/drivers/net/wireless/marvell/mwl8k.c b/drivers/net/wireless/marvell/mwl8k.c
index d55f229abeea66a1cd4cc9c4938f00170f1d59bf..47fb4b3ea004515c4c325b9b518291d07605f674 100644 (file)
--- a/drivers/net/wireless/marvell/mwl8k.c
+++ b/drivers/net/wireless/marvell/mwl8k.c
@@ -592,7 +592,7 @@ struct mwl8k_cmd_pkt {
        __u8    seq_num;
        __u8    macid;
        __le16  result;
-       char    payload[0];
+       char    payload[];
 } __packed;
 
 /*
@@ -806,7 +806,7 @@ static int mwl8k_load_firmware(struct ieee80211_hw *hw)
 struct mwl8k_dma_data {
        __le16 fwlen;
        struct ieee80211_hdr wh;
-       char data[0];
+       char data[];
 } __packed;
 
 /* Routines to add/remove DMA header from skb.  */
@@ -2955,7 +2955,7 @@ mwl8k_cmd_rf_antenna(struct ieee80211_hw *hw, int antenna, int mask)
 struct mwl8k_cmd_set_beacon {
        struct mwl8k_cmd_pkt header;
        __le16 beacon_len;
-       __u8 beacon[0];
+       __u8 beacon[];
 };
 
 static int mwl8k_cmd_set_beacon(struct ieee80211_hw *hw,