From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Jes Sorensen <Jes.Sorensen@gmail.com>,
Kalle Valo <kvalo@codeaurora.org>,
"David S. Miller" <davem@davemloft.net>,
Ping-Ke Shih <pkshih@realtek.com>,
Yan-Hsuan Chuang <yhchuang@realtek.com>
Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH][next] wireless: realtek: Replace zero-length array with flexible-array member
Date: Mon, 24 Feb 2020 18:27:46 -0600 [thread overview]
Message-ID: <20200225002746.GA26789@embeddedor> (raw)
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>
---
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
next reply other threads:[~2020-02-25 0:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-25 0:27 Gustavo A. R. Silva [this message]
2020-02-25 16:14 ` [PATCH][next] wireless: realtek: Replace zero-length array with flexible-array member Jes Sorensen
2020-03-02 13:28 ` Kalle Valo
2020-03-23 16:54 ` Kalle Valo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200225002746.GA26789@embeddedor \
--to=gustavo@embeddedor.com \
--cc=Jes.Sorensen@gmail.com \
--cc=davem@davemloft.net \
--cc=kvalo@codeaurora.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pkshih@realtek.com \
--cc=yhchuang@realtek.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).