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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id i1sm7221219pfo.212.2020.07.30.11.47.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2020 11:47:23 -0700 (PDT) Date: Thu, 30 Jul 2020 11:47:22 -0700 From: Kees Cook To: Linus Torvalds Cc: Stephen Rothwell , Emese Revfy , Linux Next Mailing List , Linux Kernel Mailing List , Willy Tarreau , Catalin Marinas , Will Deacon , Sami Tolvanen Subject: Re: linux-next: build failure after merge of the origin tree Message-ID: <202007301138.D8B018CB@keescook> References: <20200730090828.2349e159@canb.auug.org.au> <202007292007.D87DBD34B@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 30, 2020 at 11:24:44AM -0700, Linus Torvalds wrote: > On Wed, Jul 29, 2020 at 8:17 PM Kees Cook wrote: > > > > I'll look into this more tomorrow. (But yes, __latent_entropy is > > absolutely used for globals already, as you found, but this is the first > > percpu it was applied to...) > > Note that it was always per-cpu. > > The only thing that changed was that it was declared static in > lib/random.c vs being externally visible. Yup, thanks. I realized that a bit after sending my email. :) > Unrelated side note: I notice that the plugins could be simplified a > bit now that we require gcc 4.9 or later. There's a fair amount of > cruft for the earlier gcc versions. Yup -- Masahiro keeps poking the build system, but I haven't cleaned up the header file macros to keep up with the recent jumps. (It falls a bit low on my TODO list since it's a bit of a mechanical cleanup. I'm open to anyone that would like to send patches, though!) > I'm not sure how seriously the gcc plugins are actually maintained (no > offense) aside from just keeping them limping along. Does anybody > actually use them in production? I thought google had mostly moved on > to clang. They're part of regular testing, and there is ongoing development (e.g. see Alex Popov's recent series[1], which is in -next waiting for the v5.9 merge window). I hear regularly from folks using randstruct, stackleak, structleak, and latent_entropy. But yes, Google has moved to Clang where we're using Clang's implementation of structleak (auto-var-init) but there has been work to get randstruct ported (as desired by at least one Android vendor), though it's currently stalled. -Kees [1] https://lore.kernel.org/lkml/20200624123330.83226-1-alex.popov@linux.com/ -- Kees Cook