Re: [PATCH RFC] wifi: ath12k: workaround fortify warnings in ath12k_wow_convert_8023_to_80211()

Paul E. McKenney
2024-07-09T17:27:14Z

On Thu, Jul 04, 2024 at 05:43:41PM +0300, Kalle Valo wrote:
> From: Kalle Valo <quic_kvalo@quicinc.com>
>
> Johannes reported with GCC 11.4 there's a fortify warning below. The warning is
> not seen with GCC 12.1 nor 13.2. Weirdly moving the other operand of sum to the
> other side the warning goes away. This is safe to do as the value of the
> operand is check earlier. But the code looks worse with this so I'm not sure
> what to do.
>
> In file included from ./include/linux/string.h:374,
> from ./include/linux/bitmap.h:13,
> from ./include/linux/cpumask.h:13,
> from ./include/linux/sched.h:16,
> from ./include/linux/delay.h:23,
> from drivers/net/wireless/ath/ath12k/wow.c:7:
> drivers/net/wireless/ath/ath12k/wow.c: In function ‘ath12k_wow_convert_8023_to_80211.constprop’:
> ./include/linux/fortify-string.h:114:33: error: ‘__builtin_memcpy’ accessing 18446744073709551611 or more bytes at offsets 0 and 0 overlaps 9223372036854775799 bytes at offset -9223372036854775804 [-Werror=restrict]
> 114 | #define __underlying_memcpy __builtin_memcpy
> | ^
> ./include/linux/fortify-string.h:637:9: note: in expansion of macro ‘__underlying_memcpy’
> 637 | __underlying_##op(p, q, __fortify_size); | ^~~~~~~~~~~~~
> ./include/linux/fortify-string.h:682:26: note: in expansion of macro ‘__fortify_memcpy_chk’
> 682 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, | ^~~~~~~~~~~~~~~~~~~~
> drivers/net/wireless/ath/ath12k/wow.c:190:25: note: in expansion of macro ‘memcpy’
> 190 | memcpy(pat, eth_pat, eth_pat_len);
> | ^~~~~~
> ./include/linux/fortify-string.h:114:33: error: ‘__builtin_memcpy’ accessing 18446744073709551605 or more bytes at offsets 0 and 0 overlaps 9223372036854775787 bytes at offset -9223372036854775798 [-Werror=restrict]
> 114 | #define __underlying_memcpy __builtin_memcpy
> | ^
> ./include/linux/fortify-string.h:637:9: note: in expansion of macro ‘__underlying_memcpy’
> 637 | __underlying_##op(p, q, __fortify_size); | ^~~~~~~~~~~~~
> ./include/linux/fortify-string.h:682:26: note: in expansion of macro ‘__fortify_memcpy_chk’
> 682 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, | ^~~~~~~~~~~~~~~~~~~~
> drivers/net/wireless/ath/ath12k/wow.c:232:25: note: in expansion of macro ‘memcpy’
> 232 | memcpy(pat, eth_pat, eth_pat_len);
> | ^~~~~~
>
> Compile tested only.
>
> Reported-by: Johannes Berg <johannes@sipsolutions.net>
> Fixes: 4a3c212eee0e ("wifi: ath12k: add basic WoW functionalities")
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>

(Also compile retested, for whatever that is worth.)

This still shows up in allmodconfig next-20240709 builds.

Thanx, Paul

> ---
> drivers/net/wireless/ath/ath12k/wow.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath12k/wow.c b/drivers/net/wireless/ath/ath12k/wow.c
> index c5cba825a84a..e9588bb7561c 100644
> --- a/drivers/net/wireless/ath/ath12k/wow.c
> +++ b/drivers/net/wireless/ath/ath12k/wow.c
> @@ -186,7 +186,7 @@ ath12k_wow_convert_8023_to_80211(struct ath12k *ar,
> if (eth_pkt_ofs < ETH_ALEN) {
> pkt_ofs = eth_pkt_ofs + a1_ofs;
>
> - if (eth_pkt_ofs + eth_pat_len < ETH_ALEN) {
> + if (eth_pat_len < ETH_ALEN - eth_pkt_ofs) {
> memcpy(pat, eth_pat, eth_pat_len);
> memcpy(bytemask, eth_bytemask, eth_pat_len);
>
> @@ -228,7 +228,7 @@ ath12k_wow_convert_8023_to_80211(struct ath12k *ar,
> } else if (eth_pkt_ofs < prot_ofs) {
> pkt_ofs = eth_pkt_ofs - ETH_ALEN + a3_ofs;
>
> - if (eth_pkt_ofs + eth_pat_len < prot_ofs) {
> + if (eth_pat_len < prot_ofs - eth_pkt_ofs) {
> memcpy(pat, eth_pat, eth_pat_len);
> memcpy(bytemask, eth_bytemask, eth_pat_len);
>
>
> base-commit: c1cacb01f35589bd41360cdb7535afc792c08a7c
> --
> 2.39.2
>