On Sat, Oct 07, 2023 at 01:20:43AM +0000, Ping-Ke Shih wrote: > On Fri, 2023-10-06 at 13:17 -0700, Kees Cook wrote: > > > > Prepare for the coming implementation by GCC and Clang of the __counted_by > > attribute. Flexible array members annotated with __counted_by can have > > their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for > > array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > > functions). > > > > As found with Coccinelle[1], add __counted_by for struct > > rtw89_btc_btf_set_slot_table. > > > > Cc: Ping-Ke Shih <pkshih@xxxxxxxxxxx> > > Cc: Kalle Valo <kvalo@xxxxxxxxxx> > > Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx> > > Cc: linux-wireless@xxxxxxxxxxxxxxx > > Cc: linux-hardening@xxxxxxxxxxxxxxx > > Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1] > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > drivers/net/wireless/realtek/rtw89/coex.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/wireless/realtek/rtw89/coex.c b/drivers/net/wireless/realtek/rtw89/coex.c > > index 4ba8b3df70ae..d66a1152c3f5 100644 > > --- a/drivers/net/wireless/realtek/rtw89/coex.c > > +++ b/drivers/net/wireless/realtek/rtw89/coex.c > > @@ -237,7 +237,7 @@ struct rtw89_btc_btf_set_report { > > struct rtw89_btc_btf_set_slot_table { > > u8 fver; > > u8 tbl_num; > > - u8 buf[]; > > + u8 buf[] __counted_by(tbl_num); > > This struct isn't defined properly. It should be > > struct rtw89_btc_btf_set_slot_table { > u8 fver; > u8 tbl_num; > struct rtw89_btc_fbtc_slot tbl[] __counted_by(tbl_num); > } __packed; > > And, we should modify rtw89_btc_fw_set_slots() as well. > > Another struct 'rtw89_btc_btf_set_mon_reg' has similar problem. > > So, NACK this patch. I will prepare one or two patches for them next week. Ah-ha; thank you! > By the way, I have question about __counted_by(). Can I apply it to little/big- > endian 'num'? Like > > struct foo { > ... > __le32 num; > __le32 data[] __counted_by(num); > } Unfortunately not yet. I hope to see it extended in the future to allow for arbitrary expressions. For this first step, it only handles native sizes. -- Kees Cook
