From: Segher Boessenkool <segher@kernel.crashing.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anders Roxell <anders.roxell@linaro.org>,
Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
Paul Mackerras <paulus@samba.org>,
Bagas Sanjaya <bagasdotme@gmail.com>,
Yang Li <yang.lee@linux.alibaba.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: outside array bounds error on ppc64_defconfig, GCC 12.1.0
Date: Tue, 7 Jun 2022 10:04:06 -0500 [thread overview]
Message-ID: <20220607150406.GF25951@gate.crashing.org> (raw)
In-Reply-To: <87mtepns81.fsf@mpe.ellerman.id.au>
On Tue, Jun 07, 2022 at 12:05:18PM +1000, Michael Ellerman wrote:
> > arch/powerpc/lib/sstep.c:287:23: error: array subscript [3, 4] is outside array bounds of 'union <anonymous>[1]' [-Werror=array-bounds]
> > 287 | up[3] = tmp;
> > | ~~~~~~^~~~~
>
> This happens because we have a generic byte reverse function
> (do_byte_reverse()), that takes a size as a parameter. So it will
> reverse 8, 16, 32 bytes etc.
>
> In some cases the compiler can see that we're passing a pointer to
> storage that is smaller than 32 bytes, but it isn't convinced that the
> size parameter is also smaller than 32 bytes.
>
> Which I think is reasonable, the code that sets the size is separate
> from this code, so the compiler can't really deduce that it's safe.
>
> I don't see a really simple fix. I tried clamping the size parameter to
> do_byte_reverse() with max(), but that didn't work :/
-Wno-error or at least -Wno-error=array-bounds is a good, simple fix.
Segher
prev parent reply other threads:[~2022-06-07 15:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-01 2:52 outside array bounds error on ppc64_defconfig, GCC 12.1.0 Bagas Sanjaya
2022-06-07 2:05 ` Michael Ellerman
2022-06-07 14:23 ` David Laight
2022-06-07 15:15 ` Segher Boessenkool
2022-06-07 15:04 ` Segher Boessenkool [this message]
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