Use offsetof to calculate offset of a field to take advantage of
compiler built-in version when possible, and avoid UBSAN warning when
compiling with Clang:
==================================================================
UBSAN: Undefined behaviour in net/wireless/wext-core.c:525:14
member access within null pointer of type 'struct iw_point'
CPU: 3 PID: 165 Comm: kworker/u16:3 Tainted: G S W 4.19.23 #43
Workqueue: cfg80211 __cfg80211_scan_done [cfg80211]
Call trace:
dump_backtrace+0x0/0x194
show_stack+0x20/0x2c
__dump_stack+0x20/0x28
dump_stack+0x70/0x94
ubsan_epilogue+0x14/0x44
ubsan_type_mismatch_common+0xf4/0xfc
__ubsan_handle_type_mismatch_v1+0x34/0x54
wireless_send_event+0x3cc/0x470
___cfg80211_scan_done+0x13c/0x220 [cfg80211]
__cfg80211_scan_done+0x28/0x34 [cfg80211]
process_one_work+0x170/0x35c
worker_thread+0x254/0x380
kthread+0x13c/0x158
ret_from_fork+0x10/0x18
===================================================================
Signed-off-by: Pi-Hsun Shih <pihsun@xxxxxxxxxxxx>
---
Change since v1:
* Add #include <stddef.h>
---
include/uapi/linux/wireless.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h
index 86eca3208b6b..a2c006a364e0 100644
--- a/include/uapi/linux/wireless.h
+++ b/include/uapi/linux/wireless.h
@@ -74,6 +74,8 @@
#include <linux/socket.h> /* for "struct sockaddr" et al */
#include <linux/if.h> /* for IFNAMSIZ and co... */
+#include <stddef.h> /* for offsetof */
+
/***************************** VERSION *****************************/
/*
* This constant is used to know the availability of the wireless
@@ -1090,8 +1092,7 @@ struct iw_event {
/* iw_point events are special. First, the payload (extra data) come at
* the end of the event, so they are bigger than IW_EV_POINT_LEN. Second,
* we omit the pointer, so start at an offset. */
-#define IW_EV_POINT_OFF (((char *) &(((struct iw_point *) NULL)->length)) - \
- (char *) NULL)
+#define IW_EV_POINT_OFF offsetof(struct iw_point, length)
#define IW_EV_POINT_LEN (IW_EV_LCP_LEN + sizeof(struct iw_point) - \
IW_EV_POINT_OFF)
base-commit: c5db92909beddadddb705b92d3388ea50b01e1a2
--
2.24.0.393.g34dc348eaf-goog
