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([2a00:1fa0:8c7:ada9:25b2:24d8:3973:eb87]) by smtp.gmail.com with ESMTPSA id u27sm17024138lfn.87.2019.08.08.02.20.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 08 Aug 2019 02:20:08 -0700 (PDT) Subject: Re: [PATCH v6 11/14] mips: Adjust brk randomization offset to fit generic version To: Alexandre Ghiti , Andrew Morton Cc: Paul Walmsley , Luis Chamberlain , Christoph Hellwig , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Paul Burton , James Hogan , Palmer Dabbelt , Albert Ou , Alexander Viro , Kees Cook , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20190808061756.19712-1-alex@ghiti.fr> <20190808061756.19712-12-alex@ghiti.fr> From: Sergei Shtylyov Message-ID: <68ec5cf6-6ba3-68ab-aa01-668b701c642f@cogentembedded.com> Date: Thu, 8 Aug 2019 12:19:56 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190808061756.19712-12-alex@ghiti.fr> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 > Signed-off-by: Alexandre Ghiti > Acked-by: Paul Burton > Reviewed-by: Kees Cook > Reviewed-by: Luis Chamberlain > --- > 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? [...] MBR, Sergei