[PATCH net-next 08/11] ath9k: work around false-positive gcc warning

Arnd Bergmann
2020-10-26T21:33:35Z

From: Arnd Bergmann <arnd@arndb.de>

gcc-10 shows a false-positive warning with CONFIG_KASAN:

drivers/net/wireless/ath/ath9k/dynack.c: In function 'ath_dynack_sample_tx_ts':
include/linux/etherdevice.h:290:14: warning: writing 4 bytes into a region of size 0 [-Wstringop-overflow=]
290 | *(u32 *)dst = *(const u32 *)src;
| ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~

Until gcc is fixed, work around this by using memcpy() in place
of ether_addr_copy(). Hopefully gcc-11 will not have this problem.

Link: https://godbolt.org/z/sab1MK
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97490
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/net/wireless/ath/ath9k/dynack.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/dynack.c b/drivers/net/wireless/ath/ath9k/dynack.c
index fbeb4a739d32..e4eb96b26ca4 100644
--- a/drivers/net/wireless/ath/ath9k/dynack.c
+++ b/drivers/net/wireless/ath/ath9k/dynack.c
@@ -247,8 +247,14 @@ void ath_dynack_sample_tx_ts(struct ath_hw *ah, struct sk_buff *skb,
ridx = ts->ts_rateindex;

da->st_rbf.ts[da->st_rbf.t_rb].tstamp = ts->ts_tstamp;
+#if defined(CONFIG_KASAN) && (CONFIG_GCC_VERSION >= 100000) && (CONFIG_GCC_VERSION < 110000)
+ /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97490 */
+ memcpy(da->st_rbf.addr[da->st_rbf.t_rb].h_dest, hdr->addr1, ETH_ALEN);
+ memcpy(da->st_rbf.addr[da->st_rbf.t_rb].h_src, hdr->addr2, ETH_ALEN);
+#else
ether_addr_copy(da->st_rbf.addr[da->st_rbf.t_rb].h_dest, hdr->addr1);
ether_addr_copy(da->st_rbf.addr[da->st_rbf.t_rb].h_src, hdr->addr2);
+#endif

if (!(info->status.rates[ridx].flags & IEEE80211_TX_RC_MCS)) {
const struct ieee80211_rate *rate;
--
2.27.0