2023-10-11 06:37:59

by Ping-Ke Shih

Subject: [PATCH 2/2] wifi: rtw89: coex: add annotation __counted_by() to struct rtw89_btc_btf_set_mon_reg

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).

Use struct_size() and flex_array_size() helpers to calculate proper sizes
for allocation and memcpy().

Don't change logic at all, and result is identical as before.

Cc: Kees Cook <[email protected]>
Signed-off-by: Ping-Ke Shih <[email protected]>
---
drivers/net/wireless/realtek/rtw89/coex.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/coex.c b/drivers/net/wireless/realtek/rtw89/coex.c
index 9f9da122f3f8..207218cdf2c4 100644
--- a/drivers/net/wireless/realtek/rtw89/coex.c
+++ b/drivers/net/wireless/realtek/rtw89/coex.c
@@ -243,7 +243,7 @@ struct rtw89_btc_btf_set_slot_table {
struct rtw89_btc_btf_set_mon_reg {
u8 fver;
u8 reg_num;
- u8 buf[];
+ struct rtw89_btc_fbtc_mreg regs[] __counted_by(reg_num);
} __packed;

enum btc_btf_set_cx_policy {
@@ -1843,7 +1843,7 @@ static void btc_fw_set_monreg(struct rtw89_dev *rtwdev)
const struct rtw89_chip_info *chip = rtwdev->chip;
const struct rtw89_btc_ver *ver = rtwdev->btc.ver;
struct rtw89_btc_btf_set_mon_reg *monreg = NULL;
- u8 n, *ptr = NULL, ulen, cxmreg_max;
+ u8 n, ulen, cxmreg_max;
u16 sz = 0;

n = chip->mon_reg_num;
@@ -1864,16 +1864,15 @@ static void btc_fw_set_monreg(struct rtw89_dev *rtwdev)
return;
}

- ulen = sizeof(struct rtw89_btc_fbtc_mreg);
- sz = (ulen * n) + sizeof(*monreg);
+ ulen = sizeof(monreg->regs[0]);
+ sz = struct_size(monreg, regs, n);
monreg = kmalloc(sz, GFP_KERNEL);
if (!monreg)
return;

monreg->fver = ver->fcxmreg;
monreg->reg_num = n;
- ptr = &monreg->buf[0];
- memcpy(ptr, chip->mon_reg, n * ulen);
+ memcpy(monreg->regs, chip->mon_reg, flex_array_size(monreg, regs, n));
rtw89_debug(rtwdev, RTW89_DBG_BTC,
"[BTC], %s(): sz=%d ulen=%d n=%d\n",
__func__, sz, ulen, n);
--
2.25.1

2023-10-11 15:54:22

by Kees Cook

Subject: Re: [PATCH 2/2] wifi: rtw89: coex: add annotation __counted_by() to struct rtw89_btc_btf_set_mon_reg

On Wed, Oct 11, 2023 at 02:37:25PM +0800, Ping-Ke Shih 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).
>
> Use struct_size() and flex_array_size() helpers to calculate proper sizes
> for allocation and memcpy().
>
> Don't change logic at all, and result is identical as before.
>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Ping-Ke Shih <[email protected]>

Looks good too. Thanks!

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook