From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34661) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fJD0o-0001z8-Lw for qemu-devel@nongnu.org; Thu, 17 May 2018 03:07:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fJD0n-0007i8-LN for qemu-devel@nongnu.org; Thu, 17 May 2018 03:07:42 -0400 References: <1526493784-25328-1-git-send-email-eric.auger@redhat.com> <1526493784-25328-3-git-send-email-eric.auger@redhat.com> <2c55370d-fa43-12a1-5baf-ec7cf824c0dc@amsat.org> <8324a612-8785-9db9-b0d4-ab943645a16d@amsat.org> From: Auger Eric Message-ID: Date: Thu, 17 May 2018 09:07:29 +0200 MIME-Version: 1.0 In-Reply-To: <8324a612-8785-9db9-b0d4-ab943645a16d@amsat.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [Qemu-arm] [PATCH 2/2] hw/arm/smmu-common: Fix coverity issue in get_block_pte_address List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Peter Maydell Cc: qemu-arm , QEMU Developers , Eric Auger Hi Philippe, On 05/16/2018 10:01 PM, Philippe Mathieu-Daud=C3=A9 wrote: > On 05/16/2018 01:23 PM, Peter Maydell wrote: >> On 16 May 2018 at 16:16, Philippe Mathieu-Daud=C3=A9 = wrote: >>> Hi Eric, >>> >>> On 05/16/2018 03:03 PM, Eric Auger wrote: >>>> Coverity points out that this can overflow if n > 31, >>>> because it's only doing 32-bit arithmetic. Let's use 1ULL instead >>>> of 1. Also the formulae used to compute n can be replaced by >>>> the level_shift() macro. >>> >>> This level_shift() replacement doesn't seems that obvious to me, can = you >>> split it in another patch? >>> >>>> >>>> Reported-by: Peter Maydell >>>> Signed-off-by: Eric Auger >>>> --- >>>> hw/arm/smmu-common.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c >>>> index 01c7be8..3c5f724 100644 >>>> --- a/hw/arm/smmu-common.c >>>> +++ b/hw/arm/smmu-common.c >>>> @@ -83,9 +83,9 @@ static inline hwaddr get_table_pte_address(uint64_= t pte, int granule_sz) >>>> static inline hwaddr get_block_pte_address(uint64_t pte, int level, >>>> int granule_sz, uint64_t= *bsz) >>>> { >>>> - int n =3D (granule_sz - 3) * (4 - level) + 3; >>>> + int n =3D level_shift(level, granule_sz); >>> >>> Shouldn't this be level_shift(level + 1, granule_sz)? >> >> No. The two expressions are equivalent, they're >> just arranged differently: >> >> level_shift(lvl, gsz) >> =3D=3D gsz + (3 - lvl) * (gsz - 3) >> =3D=3D gsz + (4 - lvl) * (gsz - 3) - (gsz - 3) >> =3D=3D gsz - gsz + (4 - lvl) * (gsz - 3) + 3 >> =3D=3D (gsz - 3) * (4 - lvl) + 3 >=20 > Argh I failed this middle school demonstrations... >=20 > Thanks Peter :) >=20 > So for the much cleaner level_shift() use: > Reviewed-by: Philippe Mathieu-Daud=C3=A9 Thank you for the review! Eric >=20