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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id gb12sm6280279pjb.51.2021.02.04.14.17.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Feb 2021 14:17:14 -0800 (PST) Date: Thu, 4 Feb 2021 14:17:13 -0800 From: Kees Cook To: Pavel Machek Cc: Timur Tabi , Steven Rostedt , Petr Mladek , Sergey Senozhatsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, roman.fietze@magna.com, john.ogness@linutronix.de, akinobu.mita@gmail.com Subject: Re: [PATCH] lib/vsprintf: make-printk-non-secret printks all addresses as unhashed Message-ID: <202102041415.D9093ED6@keescook> References: <20210202201846.716915-1-timur@kernel.org> <20210204204835.GA7529@amd> <20210204155423.2864bf4f@gandalf.local.home> <20210204214944.GA13103@amd> <873d7e08-7a70-a1a3-f486-882d1d515965@kernel.org> <20210204221143.GB13103@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210204221143.GB13103@amd> 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 Thu, Feb 04, 2021 at 11:11:43PM +0100, Pavel Machek wrote: > On Thu 2021-02-04 15:59:21, Timur Tabi wrote: > > On 2/4/21 3:49 PM, Pavel Machek wrote: > > >This machine is insecure. Yet I don't see ascii-art *** all around.. > > > > > >"Kernel memory addresses are exposed, which is bad for security." > > > > I'll use whatever wording everyone can agree on, but I really don't see much > > difference between "which may compromise security on your system" and "which > > is bad for security". "may compromise" doesn't see any more alarmist than > > "bad". Frankly, "bad" is a very generic term. > > Well, I agree that "bad" is vague.... but original wording is simply > untrue, as printing addresses decreases robustness but can't introduce > security problem on its own. > > Being alarmist is not my complaint; being untrue is. It's just semantics. Printing addresses DOES weaken the security of a system, especially when we know attackers have and do use stuff from dmesg to tune their attacks. How about "reduces the security of your system"? -- Kees Cook