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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id e10sm493387pfc.40.2021.04.28.13.39.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 13:39:07 -0700 (PDT) Date: Wed, 28 Apr 2021 13:39:07 -0700 From: Kees Cook To: Yu-cheng Yu Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Subject: Re: [PATCH v26 8/9] x86/vdso/32: Add ENDBR to __kernel_vsyscall entry point Message-ID: <202104281339.F0CA6CA3E@keescook> References: <20210427204720.25007-1-yu-cheng.yu@intel.com> <20210427204720.25007-9-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210427204720.25007-9-yu-cheng.yu@intel.com> Received-SPF: none (chromium.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-pf1-f173.google.com; client-ip=209.85.210.173 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619642333-121454 Received-SPF: none (chromium.org>: No applicable sender policy available) receiver=imf23; identity=mailfrom; envelope-from=""; helo=smtprelay.test.hostedemail.com; client-ip=216.40.41.5 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619642355-525057 Received-SPF: none (chromium.org>: No applicable sender policy available) receiver=imf10; identity=mailfrom; envelope-from=""; helo=smtprelay.test.hostedemail.com; client-ip=216.40.41.5 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619642360-364257 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C7BBAA000396 X-Stat-Signature: 3yuhnt6re8fopjabjgf4by9o49h7tgis Received-SPF: none (chromium.org>: No applicable sender policy available) receiver=imf15; identity=mailfrom; envelope-from=""; helo=smtprelay.test.hostedemail.com; client-ip=216.40.41.5 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619642377-736149 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, Apr 27, 2021 at 01:47:19PM -0700, Yu-cheng Yu wrote: > From: "H.J. Lu" > > ENDBR is a special new instruction for the Indirect Branch Tracking (IBT) > component of CET. IBT prevents attacks by ensuring that (most) indirect > branches and function calls may only land at ENDBR instructions. Branches > that don't follow the rules will result in control flow (#CF) exceptions. > > ENDBR is a noop when IBT is unsupported or disabled. Most ENDBR > instructions are inserted automatically by the compiler, but branch > targets written in assembly must have ENDBR added manually. > > Add that to __kernel_vsyscall entry point. > > Signed-off-by: H.J. Lu Reviewed-by: Kees Cook -- Kees Cook