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[209.85.217.50]) by smtp.gmail.com with ESMTPSA id p6sm377768vke.16.2019.04.17.21.45.27 for (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Wed, 17 Apr 2019 21:45:28 -0700 (PDT) Received: by mail-vs1-f50.google.com with SMTP id t23so449873vso.10 for ; Wed, 17 Apr 2019 21:45:27 -0700 (PDT) X-Received: by 2002:a67:7c8a:: with SMTP id x132mr50675686vsc.172.1555562232106; Wed, 17 Apr 2019 21:37:12 -0700 (PDT) MIME-Version: 1.0 References: <20190417052247.17809-1-alex@ghiti.fr> <20190417052247.17809-4-alex@ghiti.fr> In-Reply-To: <20190417052247.17809-4-alex@ghiti.fr> From: Kees Cook Date: Wed, 17 Apr 2019 23:37:00 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 03/11] arm64: Consider stack randomization for mmap base only when necessary To: Alexandre Ghiti X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190417_214529_803959_6BD35223 X-CRM114-Status: GOOD ( 16.85 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Albert Ou , Kees Cook , Catalin Marinas , Palmer Dabbelt , Will Deacon , Russell King , Ralf Baechle , LKML , Linux-MM , Paul Burton , linux-riscv@lists.infradead.org, Alexander Viro , James Hogan , "linux-fsdevel@vger.kernel.org" , Andrew Morton , linux-mips@vger.kernel.org, Christoph Hellwig , linux-arm-kernel , Luis Chamberlain Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Apr 17, 2019 at 12:26 AM Alexandre Ghiti wrote: > > Do not offset mmap base address because of stack randomization if > current task does not want randomization. Maybe mention that this makes this logic match the existing x86 behavior too? > Signed-off-by: Alexandre Ghiti Acked-by: Kees Cook -Kees > --- > 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 ed4f9915f2b8..ac89686c4af8 100644 > --- a/arch/arm64/mm/mmap.c > +++ b/arch/arm64/mm/mmap.c > @@ -65,7 +65,11 @@ 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 > -- Kees Cook _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv