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 <[email protected]>
> > Cc: Kalle Valo <[email protected]>
> > Cc: "Gustavo A. R. Silva" <[email protected]>
> > Cc: [email protected]
> > Cc: [email protected]
> > Link:
> > https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> > [1]
> > Signed-off-by: Kees Cook <[email protected]>
> > ---
> > 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
