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[217.70.183.196]) by mx.google.com with ESMTPS id nq5si30507286ejb.124.2019.08.07.23.21.25 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 07 Aug 2019 23:21:25 -0700 (PDT) Received-SPF: neutral (google.com: 217.70.183.196 is neither permitted nor denied by best guess record for domain of alex@ghiti.fr) client-ip=217.70.183.196; Authentication-Results: mx.google.com; spf=neutral (google.com: 217.70.183.196 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 alex.numericable.fr (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id 1AE39E0004; Thu, 8 Aug 2019 06:21:18 +0000 (UTC) From: Alexandre Ghiti To: 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, Alexandre Ghiti Subject: [PATCH v6 03/14] arm64: Consider stack randomization for mmap base only when necessary Date: Thu, 8 Aug 2019 02:17:45 -0400 Message-Id: <20190808061756.19712-4-alex@ghiti.fr> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190808061756.19712-1-alex@ghiti.fr> References: <20190808061756.19712-1-alex@ghiti.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: Do not offset mmap base address because of stack randomization if current task does not want randomization. Note that x86 already implements this behaviour. Signed-off-by: Alexandre Ghiti Acked-by: Catalin Marinas Acked-by: Kees Cook Reviewed-by: Christoph Hellwig Reviewed-by: Luis Chamberlain --- arch/arm64/mm/mmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index bb0140afed66..e4acaead67de 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -54,7 +54,11 @@ unsigned long arch_mmap_rnd(void) static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) { unsigned long gap = rlim_stack->rlim_cur; - unsigned long pad = (STACK_RND_MASK << PAGE_SHIFT) + stack_guard_gap; + unsigned long pad = stack_guard_gap; + + /* Account for stack randomization if necessary */ + if (current->flags & PF_RANDOMIZE) + pad += (STACK_RND_MASK << PAGE_SHIFT); /* Values close to RLIM_INFINITY can overflow. */ if (gap + pad > gap) -- 2.20.1