From: Kees Cook <keescook@chromium.org>
To: Kalle Valo <kvalo@kernel.org>
Cc: Jakub Kicinski <kuba@kernel.org>,
johannes@sipsolutions.net, netdev@vger.kernel.org,
linux-wireless@vger.kernel.org, toke@toke.dk,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH net-next 2/8] wifi: ath9k: silence array-bounds warning on GCC 12
Date: Mon, 23 May 2022 12:31:23 -0700 [thread overview]
Message-ID: <202205231229.CF6B8471@keescook> (raw)
In-Reply-To: <87h75j1iej.fsf@kernel.org>
On Sat, May 21, 2022 at 09:58:28AM +0300, Kalle Valo wrote:
> + arnd, kees, lkml
>
> Jakub Kicinski <kuba@kernel.org> writes:
>
> > GCC 12 says:
> >
> > drivers/net/wireless/ath/ath9k/mac.c: In function ‘ath9k_hw_resettxqueue’:
> > drivers/net/wireless/ath/ath9k/mac.c:373:22: warning: array subscript
> > 32 is above array bounds of ‘struct ath9k_tx_queue_info[10]’
> > [-Warray-bounds]
> > 373 | qi = &ah->txq[q];
> > | ~~~~~~~^~~
> >
> > I don't know where it got the 32 from, relegate the warning to W=1+.
> >
> > Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> > ---
> > CC: toke@toke.dk
> > CC: kvalo@kernel.org
> > CC: linux-wireless@vger.kernel.org
> > ---
> > drivers/net/wireless/ath/ath9k/Makefile | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/wireless/ath/ath9k/Makefile b/drivers/net/wireless/ath/ath9k/Makefile
> > index eff94bcd1f0a..9bdfcee2f448 100644
> > --- a/drivers/net/wireless/ath/ath9k/Makefile
> > +++ b/drivers/net/wireless/ath/ath9k/Makefile
> > @@ -45,6 +45,11 @@ ath9k_hw-y:= \
> > ar9003_eeprom.o \
> > ar9003_paprd.o
> >
> > +# FIXME: temporarily silence -Warray-bounds on non W=1+ builds
> > +ifndef KBUILD_EXTRA_WARN
> > +CFLAGS_mac.o += -Wno-array-bounds
> > +endif
>
> There are now four wireless drivers which need this hack. Wouldn't it be
> easier to add -Wno-array-bounds for GCC 12 globally instead of adding
> the same hack to multiple drivers?
I finally tracked this down to a GCC 12 bug related to -fsanitize=shift:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105679
Basically all the "32" stuff comes from the index being used in a shift,
and the resulting internal GCC logic blowing up.
I was going to do a before/after build with and without -fsanitize=shift
to see how many of these false positives originate from that bug...
--
Kees Cook
prev parent reply other threads:[~2022-05-23 19:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20220520194320.2356236-1-kuba@kernel.org>
[not found] ` <20220520194320.2356236-3-kuba@kernel.org>
2022-05-21 6:58 ` [PATCH net-next 2/8] wifi: ath9k: silence array-bounds warning on GCC 12 Kalle Valo
2022-05-21 17:53 ` Jakub Kicinski
2022-05-22 12:06 ` Kalle Valo
2022-05-23 19:31 ` Kees Cook [this message]
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