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Re: [Qemu-arm] [PATCH 2/2] hw/arm/smmu-common: Fix coverity issue in get
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-arm] [PATCH 2/2] hw/arm/smmu-common: Fix coverity issue in get_block_pte_address |
Date: |
Wed, 16 May 2018 13:16:54 -0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
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 <address@hidden>
> Signed-off-by: Eric Auger <address@hidden>
> ---
> 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 = (granule_sz - 3) * (4 - level) + 3;
> + int n = level_shift(level, granule_sz);
Shouldn't this be level_shift(level + 1, granule_sz)?
Using level_shift() you replaced the trailing 3 by granule_sz. This
means the previous code was only correct for the granule_sz==3 case.
level_shift(level + 1, granule_sz)
== (granule_sz - 3) * (3 - (level + 1)) + granule_sz;
== (granule_sz - 3) * (4 - level) + granule_sz;
!= (granule_sz - 3) * (4 - level) + 3;
>
> - *bsz = 1 << n;
> + *bsz = 1ULL << n;
For the coverity fix (patch splitted):
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> return PTE_ADDRESS(pte, n);
> }
>
Regards,
Phil.
[Qemu-arm] [PATCH 1/2] hw/arm/smmuv3: Fix Coverity issue in smmuv3_record_event, Eric Auger, 2018/05/16
Re: [Qemu-arm] [PATCH 0/2] ARM SMMUv3: Fix a couple of Coverity issues, Peter Maydell, 2018/05/17