+ linux-wireless [Top-posting because the important stuff is up here, and the rest is missing from linux-wireless] Hey Pi-Hsun, Nicolas: you failed to copy linux-wireless, so no one's going to pick this patch up. Please re-send if you care. Regards, Brian On Thu, May 02, 2019 at 03:56:33PM +0800, Nicolas Boichat wrote: > On Thu, Apr 18, 2019 at 3:50 PM Pi-Hsun Shih <pihsun@xxxxxxxxxxxx> wrote: > > > > 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> > > The warning from clang is spurious, but in another case, we felt that > the cleanup was worth it, nevertheless > (https://lore.kernel.org/patchwork/patch/1050040/). > > Reviewed-By: Nicolas Boichat <drinkcat@xxxxxxxxxxxx> > > > --- > > include/uapi/linux/wireless.h | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/include/uapi/linux/wireless.h b/include/uapi/linux/wireless.h > > index 86eca3208b6b..f259cca5cc2b 100644 > > --- a/include/uapi/linux/wireless.h > > +++ b/include/uapi/linux/wireless.h > > @@ -1090,8 +1090,7 @@ 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) > > > > -- > > 2.21.0.392.gf8f6787159e-goog > >
