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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id ji18-20020a170903325200b001b9da8b4eb7sm2270966plb.35.2023.08.25.15.29.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Aug 2023 15:29:58 -0700 (PDT) Date: Fri, 25 Aug 2023 15:29:58 -0700 From: Kees Cook To: Florent Revest Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, catalin.marinas@arm.com, anshuman.khandual@arm.com, joey.gouly@arm.com, mhocko@suse.com, david@redhat.com, peterx@redhat.com, izbyshev@ispras.ru, broonie@kernel.org, szabolcs.nagy@arm.com, kpsingh@kernel.org, gthelen@google.com, toiwoton@gmail.com Subject: Re: [PATCH v3 3/5] mm: Make PR_MDWE_REFUSE_EXEC_GAIN an unsigned long Message-ID: <202308251529.43BB30B9A3@keescook> References: <20230704153630.1591122-1-revest@chromium.org> <20230704153630.1591122-4-revest@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230704153630.1591122-4-revest@chromium.org> X-Rspamd-Queue-Id: 5234E1A0012 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: drq4sax9bhst4d3xfeway96is6q8iyck X-HE-Tag: 1693002600-248122 X-HE-Meta: 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 uHU3oU6K 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 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 Tue, Jul 04, 2023 at 05:36:27PM +0200, Florent Revest wrote: > Defining a prctl flag as an int is a footgun because on a 64 bit machine > and with a variadic implementation of prctl (like in musl and glibc), > when used directly as a prctl argument, it can get casted to long with > garbage upper bits which would result in unexpected behaviors. > > This patch changes the constant to an unsigned long to eliminate that > possibilities. This does not break UAPI. > > Fixes: b507808ebce2 ("mm: implement memory-deny-write-execute as a prctl") > Cc: linux-stable@vger.kernel.org > Signed-off-by: Florent Revest Ah yes. I remember this pain with seccomp. :) Reviewed-by: Kees Cook -- Kees Cook