From: Alexandre Ghiti <alex@ghiti.fr>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
Kees Cook <keescook@chromium.org>,
linux-mm@kvack.org, Catalin Marinas <catalin.marinas@arm.com>,
Palmer Dabbelt <palmer@sifive.com>,
Will Deacon <will.deacon@arm.com>,
Russell King <linux@armlinux.org.uk>,
Ralf Baechle <ralf@linux-mips.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Luis Chamberlain <mcgrof@kernel.org>,
Paul Burton <paul.burton@mips.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
James Hogan <jhogan@kernel.org>,
linux-riscv@lists.infradead.org, linux-mips@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org,
Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v6 11/14] mips: Adjust brk randomization offset to fit generic version
Date: Fri, 9 Aug 2019 11:45:51 +0200 [thread overview]
Message-ID: <7b7e256d-5106-3022-9ded-0af4193b6b8b@ghiti.fr> (raw)
In-Reply-To: <68ec5cf6-6ba3-68ab-aa01-668b701c642f@cogentembedded.com>
On 8/8/19 11:19 AM, Sergei Shtylyov wrote:
> Hello!
>
> On 08.08.2019 9:17, Alexandre Ghiti wrote:
>
>> This commit simply bumps up to 32MB and 1GB the random offset
>> of brk, compared to 8MB and 256MB, for 32bit and 64bit respectively.
>>
>> Suggested-by: Kees Cook <keescook@chromium.org>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>> Acked-by: Paul Burton <paul.burton@mips.com>
>> Reviewed-by: Kees Cook <keescook@chromium.org>
>> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
>> ---
>> arch/mips/mm/mmap.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
>> index a7e84b2e71d7..ff6ab87e9c56 100644
>> --- a/arch/mips/mm/mmap.c
>> +++ b/arch/mips/mm/mmap.c
> [...]
>> @@ -189,11 +190,11 @@ static inline unsigned long brk_rnd(void)
>> unsigned long rnd = get_random_long();
>> rnd = rnd << PAGE_SHIFT;
>> - /* 8MB for 32bit, 256MB for 64bit */
>> + /* 32MB for 32bit, 1GB for 64bit */
>> if (TASK_IS_32BIT_ADDR)
>> - rnd = rnd & 0x7ffffful;
>> + rnd = rnd & (SZ_32M - 1);
>> else
>> - rnd = rnd & 0xffffffful;
>> + rnd = rnd & (SZ_1G - 1);
>
> Why not make these 'rnd &= SZ_* - 1', while at it anyways?
You're right, I could have. Again, this code gets removed afterwards, so
I think it's ok
to leave it as is.
Anyway, thanks for your remarks Sergei !
Alex
>
> [...]
>
> MBR, Sergei
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2019-08-09 9:46 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 6:17 [PATCH v6 00/14] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 01/14] mm, fs: Move randomize_stack_top from fs to mm Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 02/14] arm64: Make use of is_compat_task instead of hardcoding this test Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 03/14] arm64: Consider stack randomization for mmap base only when necessary Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 04/14] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 05/14] arm64, mm: Make randomization selected by generic topdown mmap layout Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 06/14] arm: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 07/14] arm: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 08/14] arm: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 09/14] mips: Properly account for stack randomization and stack guard gap Alexandre Ghiti
2019-08-08 9:16 ` Sergei Shtylyov
2019-08-09 9:44 ` Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 10/14] mips: Use STACK_TOP when computing mmap base address Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 11/14] mips: Adjust brk randomization offset to fit generic version Alexandre Ghiti
2019-08-08 9:19 ` Sergei Shtylyov
2019-08-09 9:45 ` Alexandre Ghiti [this message]
2019-08-08 6:17 ` [PATCH v6 12/14] mips: Replace arch specific way to determine 32bit task with " Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 13/14] mips: Use generic mmap top-down layout and brk randomization Alexandre Ghiti
2019-08-08 6:17 ` [PATCH v6 14/14] riscv: Make mmap allocation top-down by default Alexandre Ghiti
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