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[217.70.183.193]) by mx.google.com with ESMTPS id gs1si653640ejb.18.2019.04.17.23.04.14 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Apr 2019 23:04:14 -0700 (PDT) Received-SPF: neutral (google.com: 217.70.183.193 is neither permitted nor denied by best guess record for domain of alex@ghiti.fr) client-ip=217.70.183.193; Authentication-Results: mx.google.com; spf=neutral (google.com: 217.70.183.193 is neither permitted nor denied by best guess record for domain of alex@ghiti.fr) smtp.mailfrom=alex@ghiti.fr X-Originating-IP: 79.86.19.127 Received: from [192.168.0.11] (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id DC0F4240004; Thu, 18 Apr 2019 06:04:08 +0000 (UTC) Subject: Re: [PATCH v3 06/11] arm: Use STACK_TOP when computing mmap base address To: Kees Cook Cc: Andrew Morton , Christoph Hellwig , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Paul Burton , James Hogan , Palmer Dabbelt , Albert Ou , Alexander Viro , Luis Chamberlain , LKML , linux-arm-kernel , linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, "linux-fsdevel@vger.kernel.org" , Linux-MM References: <20190417052247.17809-1-alex@ghiti.fr> <20190417052247.17809-7-alex@ghiti.fr> From: Alex Ghiti Message-ID: <9fdc1de9-8552-da1b-7d05-0596969ddad2@ghiti.fr> Date: Thu, 18 Apr 2019 02:04:08 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: sv-FI 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: On 4/18/19 1:27 AM, Kees Cook wrote: > On Wed, Apr 17, 2019 at 12:29 AM Alexandre Ghiti wrote: >> mmap base address must be computed wrt stack top address, using TASK_SIZE >> is wrong since STACK_TOP and TASK_SIZE are not equivalent. >> >> Signed-off-by: Alexandre Ghiti >> --- >> arch/arm/mm/mmap.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c >> index bff3d00bda5b..0b94b674aa91 100644 >> --- a/arch/arm/mm/mmap.c >> +++ b/arch/arm/mm/mmap.c >> @@ -19,7 +19,7 @@ >> >> /* gap between mmap and stack */ >> #define MIN_GAP (128*1024*1024UL) >> -#define MAX_GAP ((TASK_SIZE)/6*5) >> +#define MAX_GAP ((STACK_TOP)/6*5) > Parens around STACK_TOP aren't needed, but you'll be removing it > entirely, so I can't complain. ;) > >> #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) >> >> static int mmap_is_legacy(struct rlimit *rlim_stack) >> @@ -51,7 +51,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) >> else if (gap > MAX_GAP) >> gap = MAX_GAP; >> >> - return PAGE_ALIGN(TASK_SIZE - gap - rnd); >> + return PAGE_ALIGN(STACK_TOP - gap - rnd); >> } >> >> /* >> -- >> 2.20.1 >> > Acked-by: Kees Cook Thanks ! >