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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id 192sm5554039wme.13.2019.04.19.01.51.42 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 19 Apr 2019 01:51:43 -0700 (PDT) Date: Fri, 19 Apr 2019 10:51:40 +0200 From: Ingo Molnar To: "Saidi, Ali" Cc: Kees Cook , Michal Hocko , Matthew Wilcox , Jann Horn , Dave Hansen , "Liguori, Anthony" , Peter Zijlstra , Catalin Marinas , X86 ML , Will Deacon , LKML , Ingo Molnar , Borislav Petkov , "Woodhouse, David" , Andy Lutomirski , "H. Peter Anvin" , Andrew Morton , Thomas Gleixner , linux-arm-kernel Subject: Re: [PATCH 2/2] x86/mmap: handle worst-case heap randomization in mmap_base Message-ID: <20190419085140.GA50390@gmail.com> References: <20190312173248.13490-1-alisaidi@amazon.com> <20190312173248.13490-3-alisaidi@amazon.com> <34381CFC-A90F-4979-9802-2BA0E6539C68@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <34381CFC-A90F-4979-9802-2BA0E6539C68@amazon.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Saidi, Ali wrote: > On 3/27/19, 2:52 PM, "linux-arm-kernel on behalf of Kees Cook" wrote: > > Adding some more people to CC... what do people think about this > moving of the brk to ELF_ET_DYN_BASE in this corner-case? Anything > that worked before should still work (i.e. the ultimately-launched > binary already had the brk very far from its text, so this should be > no different from a COMPAT_BRK standpoint). The only risk I see here > is that if someone started to suddenly depend on the entire memory > space above the mmap region being available when launching binaries > via a direct loader execs... which seems highly unlikely, I'd hope: > this would mean a binary would not work when execed normally. > > Kees' proposal addresses the issue for me. Anyone have concerns on this proposed solution? I'd suggest incorporating all feedback and sending a v2 series - it's much easier to get people's attention via code submitted. ;-) Thanks, Ingo