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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id l9-20020a170903244900b001ac94b33ab1sm3975861pls.304.2023.05.10.09.07.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 May 2023 09:07:50 -0700 (PDT) Message-ID: <645bc156.170a0220.62d12.7fb3@mx.google.com> X-Google-Original-Message-ID: <202305100907.@keescook> Date: Wed, 10 May 2023 09:07:50 -0700 From: Kees Cook To: Alexander Potapenko Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, elver@google.com, dvyukov@google.com, kasan-dev@googlegroups.com, andy@kernel.org, ndesaulniers@google.com, nathan@kernel.org Subject: Re: [PATCH] string: use __builtin_memcpy() in strlcpy/strlcat References: <20230424112313.3408363-1-glider@google.com> <6446ad55.170a0220.c82cd.cedc@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E837180153 X-Stat-Signature: gbin18yb7stjg8c8uhnxzktfg919biag X-HE-Tag: 1683734872-946929 X-HE-Meta: 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 gCBo9LcN i+NrUbea17NNyhFMpYbNEfn17Ijoflb9KvfM6DPi08l6L9HQ+hlSlUOqkBMuqSZtcxGev/4LJ5pBYaZAZUnCZSw4FNcv8WjUNh0JQky60V79Dwywqn4hST64Qh56wFQFNGMzYEOVHLbeDfY36bAOYNkmWTA9lZkiJAYDE/lGSt7Uxp7h4BL6/Xf4qGEhNexUbFP3aOojF4yz6QGYey1D8rckkRDQJd8UMusMIynnlRZ1Qe/xd6X/BZZr7881Dl2OttF3mTixhWh3tsVdeQf+0Z4Lk7EG2Fynhrm6zvpcmjetNdm/QYHyy9JyDWIG0A7gbcmNvuvpvXebGY3QOfYM9HAzcmiDOLn67FyWTJQz7cZUO5d+fJn4SyhbZzLeaYZMByiSPo0AL1yiMwnxKKbRQJEfTEY1gPIVTA2K0K+j3rOFRZ2U= 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 Fri, Apr 28, 2023 at 03:48:28PM +0200, Alexander Potapenko wrote: > > > > I *think* this isn't a problem for CONFIG_FORTIFY, since these will be > > replaced and checked separately -- but it still seems strange that you > > need to explicitly use __builtin_memcpy. > > > > Does this end up changing fortify coverage? > > Is fortify relevant here? Note that the whole file is compiled with > __NO_FORTIFY. Yeah, agreed. I think I was just curious if that got verified. I'm good with this. Acked-by: Kees Cook -- Kees Cook