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@xxxxxxxxxxxxxx>
---
drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h | 2 +-
drivers/net/wireless/realtek/rtlwifi/wifi.h | 6 +++---
drivers/net/wireless/realtek/rtw88/fw.h | 2 +-
drivers/net/wireless/realtek/rtw88/main.h | 2 +-
4 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
index 6598c8d786ea..440d164443bc 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
+++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h
@@ -627,7 +627,7 @@ struct rtl8xxxu_firmware_header {
u32 reserved4;
u32 reserved5;
- u8 data[0];
+ u8 data[];
};
/*
diff --git a/drivers/net/wireless/realtek/rtlwifi/wifi.h b/drivers/net/wireless/realtek/rtlwifi/wifi.h
index 1cff9f07c9e9..13421cf2d201 100644
--- a/drivers/net/wireless/realtek/rtlwifi/wifi.h
+++ b/drivers/net/wireless/realtek/rtlwifi/wifi.h
@@ -1051,13 +1051,13 @@ struct rtl_hdr_3addr {
u8 addr2[ETH_ALEN];
u8 addr3[ETH_ALEN];
__le16 seq_ctl;
- u8 payload[0];
+ u8 payload[];
} __packed;
struct rtl_info_element {
u8 id;
u8 len;
- u8 data[0];
+ u8 data[];
} __packed;
struct rtl_probe_rsp {
@@ -1068,7 +1068,7 @@ struct rtl_probe_rsp {
/*SSID, supported rates, FH params, DS params,
* CF params, IBSS params, TIM (if beacon), RSN
*/
- struct rtl_info_element info_element[0];
+ struct rtl_info_element info_element[];
} __packed;
/*LED related.*/
diff --git a/drivers/net/wireless/realtek/rtw88/fw.h b/drivers/net/wireless/realtek/rtw88/fw.h
index ccd27bd45775..414827800a5f 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.h
+++ b/drivers/net/wireless/realtek/rtw88/fw.h
@@ -36,7 +36,7 @@ enum rtw_c2h_cmd_id_ext {
struct rtw_c2h_cmd {
u8 id;
u8 seq;
- u8 payload[0];
+ u8 payload[];
} __packed;
enum rtw_rsvd_packet_type {
diff --git a/drivers/net/wireless/realtek/rtw88/main.h b/drivers/net/wireless/realtek/rtw88/main.h
index c074cef22120..46c0ebceb177 100644
--- a/drivers/net/wireless/realtek/rtw88/main.h
+++ b/drivers/net/wireless/realtek/rtw88/main.h
@@ -1641,7 +1641,7 @@ struct rtw_dev {
struct rtw_wow_param wow;
/* hci related data, must be last */
- u8 priv[0] __aligned(sizeof(void *));
+ u8 priv[] __aligned(sizeof(void *));
};
#include "hci.h"
--
2.25.0
