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Subject: Re: [PATCH v3 02/11] arm64: Make use of is_compat_task instead of
 hardcoding this test
To:     Kees Cook <keescook@chromium.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>,
        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paul.burton@mips.com>,
        James Hogan <jhogan@kernel.org>,
        Palmer Dabbelt <palmer@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Luis Chamberlain <mcgrof@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>
References: <20190417052247.17809-1-alex@ghiti.fr>
 <20190417052247.17809-3-alex@ghiti.fr>
 <CAGXu5jKVa2YgAkWH1e26kxd2j6C4WsJ38+Z3K1z7JRvr_jDX6Q@mail.gmail.com>
From:   Alex Ghiti <alex@ghiti.fr>
Message-ID: <1f63cf5a-6bbe-fa55-75c0-20322d8a7f36@ghiti.fr>
Date:   Thu, 18 Apr 2019 01:23:38 -0400
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On 4/18/19 12:32 AM, Kees Cook wrote:
> On Wed, Apr 17, 2019 at 12:25 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>> Each architecture has its own way to determine if a task is a compat task,
>> by using is_compat_task in arch_mmap_rnd, it allows more genericity and
>> then it prepares its moving to mm/.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Acked-by: Kees Cook <keescook@chromium.org>


Thanks !


> -Kees
>
>> ---
>>   arch/arm64/mm/mmap.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
>> index 842c8a5fcd53..ed4f9915f2b8 100644
>> --- a/arch/arm64/mm/mmap.c
>> +++ b/arch/arm64/mm/mmap.c
>> @@ -54,7 +54,7 @@ unsigned long arch_mmap_rnd(void)
>>          unsigned long rnd;
>>
>>   #ifdef CONFIG_COMPAT
>> -       if (test_thread_flag(TIF_32BIT))
>> +       if (is_compat_task())
>>                  rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
>>          else
>>   #endif
>> --
>> 2.20.1
>>
>