| Message ID | 20200225003408.GA28675@embeddedor (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 398978f7dfa551abff9361f40db951c3c982fa5e |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | [next] wireless: ti: Replace zero-length array with flexible-array member | expand |
"Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote: > 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> Patch applied to wireless-drivers-next.git, thanks. 398978f7dfa5 wireless: ti: Replace zero-length array with flexible-array member
diff --git a/drivers/net/wireless/ti/wl1251/cmd.h b/drivers/net/wireless/ti/wl1251/cmd.h index 1c1a591c6055..e5874186f9d7 100644 --- a/drivers/net/wireless/ti/wl1251/cmd.h +++ b/drivers/net/wireless/ti/wl1251/cmd.h @@ -90,7 +90,7 @@ struct wl1251_cmd_header { u16 id; u16 status; /* payload */ - u8 data[0]; + u8 data[]; } __packed; struct wl1251_command { @@ -281,7 +281,7 @@ struct wl1251_cmd_packet_template { struct wl1251_cmd_header header; __le16 size; - u8 data[0]; + u8 data[]; } __packed; #define TIM_ELE_ID 5 diff --git a/drivers/net/wireless/ti/wl1251/wl12xx_80211.h b/drivers/net/wireless/ti/wl1251/wl12xx_80211.h index 7fabe702c4cc..7e28fe435b43 100644 --- a/drivers/net/wireless/ti/wl1251/wl12xx_80211.h +++ b/drivers/net/wireless/ti/wl1251/wl12xx_80211.h @@ -65,7 +65,7 @@ struct ieee80211_header { u8 sa[ETH_ALEN]; u8 bssid[ETH_ALEN]; __le16 seq_ctl; - u8 payload[0]; + u8 payload[]; } __packed; struct wl12xx_ie_header { diff --git a/drivers/net/wireless/ti/wlcore/acx.h b/drivers/net/wireless/ti/wlcore/acx.h index a265fba0cb4c..c725f5855c13 100644 --- a/drivers/net/wireless/ti/wlcore/acx.h +++ b/drivers/net/wireless/ti/wlcore/acx.h @@ -938,7 +938,7 @@ struct acx_rx_filter_cfg { u8 action; u8 num_fields; - u8 fields[0]; + u8 fields[]; } __packed; struct acx_roaming_stats { diff --git a/drivers/net/wireless/ti/wlcore/boot.h b/drivers/net/wireless/ti/wlcore/boot.h index 14b367e98dce..24a2dfcb41ea 100644 --- a/drivers/net/wireless/ti/wlcore/boot.h +++ b/drivers/net/wireless/ti/wlcore/boot.h @@ -26,7 +26,7 @@ struct wl1271_static_data { u8 fw_version[WL1271_FW_VERSION_MAX_LEN]; u32 hw_version; u8 tx_power_table[WL1271_NO_SUBBANDS][WL1271_NO_POWER_LEVELS]; - u8 priv[0]; + u8 priv[]; }; /* number of times we try to read the INIT interrupt */ diff --git a/drivers/net/wireless/ti/wlcore/cmd.h b/drivers/net/wireless/ti/wlcore/cmd.h index bfad7b5a1ac6..f2609d5b6bf7 100644 --- a/drivers/net/wireless/ti/wlcore/cmd.h +++ b/drivers/net/wireless/ti/wlcore/cmd.h @@ -209,7 +209,7 @@ struct wl1271_cmd_header { __le16 id; __le16 status; /* payload */ - u8 data[0]; + u8 data[]; } __packed; #define WL1271_CMD_MAX_PARAMS 572 diff --git a/drivers/net/wireless/ti/wlcore/conf.h b/drivers/net/wireless/ti/wlcore/conf.h index 6116383ee248..31be425f2332 100644 --- a/drivers/net/wireless/ti/wlcore/conf.h +++ b/drivers/net/wireless/ti/wlcore/conf.h @@ -1150,7 +1150,7 @@ struct wlcore_conf { struct wlcore_conf_file { struct wlcore_conf_header header; struct wlcore_conf core; - u8 priv[0]; + u8 priv[]; } __packed; #endif diff --git a/drivers/net/wireless/ti/wlcore/wl12xx_80211.h b/drivers/net/wireless/ti/wlcore/wl12xx_80211.h index 181be725eff8..1dd7ecc11f86 100644 --- a/drivers/net/wireless/ti/wlcore/wl12xx_80211.h +++ b/drivers/net/wireless/ti/wlcore/wl12xx_80211.h @@ -66,7 +66,7 @@ struct ieee80211_header { u8 sa[ETH_ALEN]; u8 bssid[ETH_ALEN]; __le16 seq_ctl; - u8 payload[0]; + u8 payload[]; } __packed; struct wl12xx_ie_header {
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/ti/wl1251/cmd.h | 4 ++-- drivers/net/wireless/ti/wl1251/wl12xx_80211.h | 2 +- drivers/net/wireless/ti/wlcore/acx.h | 2 +- drivers/net/wireless/ti/wlcore/boot.h | 2 +- drivers/net/wireless/ti/wlcore/cmd.h | 2 +- drivers/net/wireless/ti/wlcore/conf.h | 2 +- drivers/net/wireless/ti/wlcore/wl12xx_80211.h | 2 +- 7 files changed, 8 insertions(+), 8 deletions(-)