Re: [PATCH 2/2] [v2] wifi: ath9k: fix fortify warnings

["Toke Høiland-Jørgensen" <toke@toke.dk>]

Dmitry Antipov <dmantipov@yandex.ru> writes:

> When compiling with gcc 13.1 and CONFIG_FORTIFY_SOURCE=y,
> I've noticed the following:
>
> In function ‘fortify_memcpy_chk’,
>     inlined from ‘ath_tx_complete_aggr’ at drivers/net/wireless/ath/ath9k/xmit.c:556:4,
>     inlined from ‘ath_tx_process_buffer’ at drivers/net/wireless/ath/ath9k/xmit.c:773:3:
> ./include/linux/fortify-string.h:529:25: warning: call to ‘__read_overflow2_field’
> declared with attribute warning: detected read beyond size of field (2nd parameter);
> maybe use struct_group()? [-Wattribute-warning]
>   529 |                         __read_overflow2_field(q_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> In function ‘fortify_memcpy_chk’,
>     inlined from ‘ath_tx_count_frames’ at drivers/net/wireless/ath/ath9k/xmit.c:473:3,
>     inlined from ‘ath_tx_complete_aggr’ at drivers/net/wireless/ath/ath9k/xmit.c:572:2,
>     inlined from ‘ath_tx_process_buffer’ at drivers/net/wireless/ath/ath9k/xmit.c:773:3:
> ./include/linux/fortify-string.h:529:25: warning: call to ‘__read_overflow2_field’
> declared with attribute warning: detected read beyond size of field (2nd parameter);
> maybe use struct_group()? [-Wattribute-warning]
>   529 |                         __read_overflow2_field(q_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> In both cases, the compiler complains on:
>
> memcpy(ba, &ts->ba_low, WME_BA_BMP_SIZE >> 3);
>
> which is the legal way to copy both 'ba_low' and following 'ba_high'
> members of 'struct ath_tx_status' at once (that is, issue one 8-byte
> 'memcpy()' for two 4-byte fields). Since the fortification logic seems
> interprets this trick as an attempt to overread 4-byte 'ba_low', silence
> relevant warnings by using the convenient 'struct_group()' quirk.
>
> Suggested-by: Johannes Berg <johannes@sipsolutions.net>
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>

Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>