From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D285CC352AD for ; Thu, 26 Sep 2019 18:38:42 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8A65A206E0 for ; Thu, 26 Sep 2019 18:38:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="GIG4pntI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A65A206E0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 46fNww4pZXzDqkG for ; Fri, 27 Sep 2019 04:38:40 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=chromium.org (client-ip=2607:f8b0:4864:20::542; helo=mail-pg1-x542.google.com; envelope-from=keescook@chromium.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.b="GIG4pntI"; dkim-atps=neutral Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 46fN0N1zndzDqqW for ; Fri, 27 Sep 2019 03:56:36 +1000 (AEST) Received: by mail-pg1-x542.google.com with SMTP id y35so1985736pgl.1 for ; Thu, 26 Sep 2019 10:56:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=yn5wfwJoFu2XxkEapi5oUode7Z6ofSq2WooR/oMOeig=; b=GIG4pntI4mSLZBUOLoFMk4guSw8F6GtVAwhEFiBddEsAgwrkRwPjIGbLRlxFjf3FFl AAkc2fNz+FhNHp9iA1Gn1CLcywcbJ+TQMeOOKdi3rLClFQao449j+D61pfii2Lo6mCp9 gdFOurgujqWI728AB8TNIMWAJHUqnNxeyVafk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=yn5wfwJoFu2XxkEapi5oUode7Z6ofSq2WooR/oMOeig=; b=QrKVUxbTdaFhweCT+bxozhFQwBcDBNEIQdHFZSAcoQBZljUCPk7luk84ulnCO/72Z3 Hj5awxW67r2u3r0GqqDqQtWZO7g8GDbFTrzD9u4wtJZESQxgoHCufoCqO3Um7+VWHnmW VYnfJ8sa045wKl0eGYG0mnrsV3BsqwiegpJ6JBJWyfmPuADYpoAk9HaSG0Aa/Znp4IWh zR/b0CrR+RfBH1LCW2YcR/l4BDJlpW0ySO6zzeT0DhRV2PSUjgfF9sMDSvu+JMySC1T7 gW2d5YHN23YuxourRFw+SMA0JHeQpbpi01+UbpkogJF/WhIvAN4g/YP737ymDUoXL8yV V9Yg== X-Gm-Message-State: APjAAAWzV3GRqCsAaG1PXSztQzaKe7Btkfo5cfbow8uVh4PmKdBMOQRm 00LuYfnBiJju24m7lQxvvrHZEA== X-Google-Smtp-Source: APXvYqztKKvfKjgB5MJEkhZ1uiyu1Mkac35wqulYkyxXb+7C2TAggJBadFx7VmxAR9W2f3IICOin9w== X-Received: by 2002:aa7:920d:: with SMTP id 13mr5075737pfo.17.1569520593466; Thu, 26 Sep 2019 10:56:33 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id x6sm7506434pfd.53.2019.09.26.10.56.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Sep 2019 10:56:30 -0700 (PDT) From: Kees Cook To: Thomas Gleixner Subject: [PATCH 29/29] x86: Use INT3 instead of NOP for linker fill bytes Date: Thu, 26 Sep 2019 10:56:02 -0700 Message-Id: <20190926175602.33098-30-keescook@chromium.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190926175602.33098-1-keescook@chromium.org> References: <20190926175602.33098-1-keescook@chromium.org> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Michal Simek , linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, Kees Cook , Arnd Bergmann , linux-xtensa@linux-xtensa.org, linux-kernel@vger.kernel.org, Dave Hansen , x86@kernel.org, Yoshinori Sato , Ingo Molnar , Borislav Petkov , linux-parisc@vger.kernel.org, Andy Lutomirski , "H. Peter Anvin" , Rick Edgecombe , linuxppc-dev@lists.ozlabs.org, linux-c6x-dev@linux-c6x.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Instead of using 0x90 (NOP) to fill bytes between functions, which makes it easier to sloppily target functions in function pointer overwrite attacks, fill with 0xCC (INT3) to force a trap. Also drops the space between "=" and the value to better match the binutils documentation https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html#Output-Section-Fill Example "objdump -d" before: ... ffffffff810001e0 : ffffffff810001e0: 48 8b 25 e1 b1 51 01 mov 0x151b1e1(%rip),%rsp # ffffffff8251b3c8 ffffffff810001e7: e9 d5 fe ff ff jmpq ffffffff810000c1 ffffffff810001ec: 90 nop ffffffff810001ed: 90 nop ffffffff810001ee: 90 nop ffffffff810001ef: 90 nop ffffffff810001f0 <__startup_64>: ... After: ... ffffffff810001e0 : ffffffff810001e0: 48 8b 25 41 79 53 01 mov 0x1537941(%rip),%rsp # ffffffff82537b28 ffffffff810001e7: e9 d5 fe ff ff jmpq ffffffff810000c1 ffffffff810001ec: cc int3 ffffffff810001ed: cc int3 ffffffff810001ee: cc int3 ffffffff810001ef: cc int3 ffffffff810001f0 <__startup_64>: ... Signed-off-by: Kees Cook --- arch/x86/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index a5c8571e4967..a37817fafb22 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -144,7 +144,7 @@ SECTIONS *(.text.__x86.indirect_thunk) __indirect_thunk_end = .; #endif - } :text = 0x9090 + } :text =0xcccc /* End of text section, which should occupy whole number of pages */ _etext = .; -- 2.17.1