Johannes Berg <johannes@xxxxxxxxxxxxxxxx> writes: > On Mon, 2020-11-02 at 18:26 +0200, Kalle Valo wrote: >> Arnd Bergmann <arnd@xxxxxxxxxx> writes: >> >> > From: Arnd Bergmann <arnd@xxxxxxxx> >> > >> > 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@xxxxxxxx> >> > --- >> > 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 >> >> Isn't there a better way to handle this? I really would not want >> checking for GCC versions become a common approach in drivers. >> >> I even think that using memcpy() always is better than the ugly ifdef. > > If you put memcpy() always somebody will surely go and clean it up to > use ether_addr_copy() soon ... I can always add a comment and hope that the cleanup people read comments :) I did that now in the pending branch: https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=25cfc077bd7a798d1aa527ad2aa9932bb3284376 Does that look ok? I prefer that over the ifdef. -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
