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=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=ham 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 5DA1CC433E0 for ; Tue, 19 May 2020 21:06:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 204AA20758 for ; Tue, 19 May 2020 21:06:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JHczdhHq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726447AbgESVF7 (ORCPT ); Tue, 19 May 2020 17:05:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725998AbgESVF6 (ORCPT ); Tue, 19 May 2020 17:05:58 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDB0AC08C5C0 for ; Tue, 19 May 2020 14:05:58 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id f6so406993pgm.1 for ; Tue, 19 May 2020 14:05:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=FAwUQNuHSy6Ybc5wRFORWg7jUHg+WoIVkThuFrr1qaY=; b=JHczdhHqwHYzn7QC3lQ50mLKHxj5rSbqKh2dG7kr5iitxnv3LOJivjRGJSJ7IhkIyc p3BQKH8GIxZRjKPN41CX9TJq/diDBntuBCHKTUQta19KKhoyto4+LXcD7E1pE3DGcE95 bSFSVMHX1pmFD6/7ZbzVrExuN1JZVnwa6rIbAzLgFawXoHkbyAzTynGOAUSohiJdnbcA IGS+WnYdqHM5V6xvzkzXq9A3mFYY5JZbfk7IY85eh3/DwYFygbTm8jO1MQQVk9mDQmxf CiQjN0VdLdrW6hV1/WkAZRT//hJqF8uVoX3vKuR1AgZ9ZNgYMNQUFXM7EBAAcuwuRj/h mjBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=FAwUQNuHSy6Ybc5wRFORWg7jUHg+WoIVkThuFrr1qaY=; b=UMgdPX/XgZc0DNkWCX2VM6X0PkGDbS5UHdiEawNP5Vf6cTJYTJbSUeoK1EoDa0I0+p 5KKZhDnBYMB8/+S6LBSMeqWnFAMaKmxPxForNU1DmyUI6Qs5JsIV+8DrtenVC4XuHzEY tkS6zHptF2hcvddKHUBmpLpht5a8a/xCUpM+Mdq94iK6kO1vO5DdhxN8rGuZBl3mpPy+ qVvF8dgzZqs2Lp1CAQHsACLmURSbnaUEmNIQOnSqZpiUSMdDeaCYcct5tUdlzEXE5JEt DS3aP2zRFAYLZ9D8PknhkN6Cws4ENDA1sP5DizXP2SmuOcybRWCo9M2C6gvQ83nhpw7C tzFQ== X-Gm-Message-State: AOAM533JJxT1FRwOj6DzEIHbweG+W7tKOue5i35Om4+eJu+XijeAFXri 01U1888NLDX+WPyZcmBCAbX1uan4C8VQhUmRQ/zpNQ== X-Google-Smtp-Source: ABdhPJx+hHEmFNLYtQfsF2N+ckL+kDTsB3iOv+fjCxCZt6tEuTwRQbefgSTruhEpXmbUKSlA2ZnKNtPUTPO7kDDeRfk= X-Received: by 2002:a63:2bd3:: with SMTP id r202mr1039983pgr.130.1589922357767; Tue, 19 May 2020 14:05:57 -0700 (PDT) MIME-Version: 1.0 References: <20200519182459.87166-1-elver@google.com> In-Reply-To: <20200519182459.87166-1-elver@google.com> From: Andrey Konovalov Date: Tue, 19 May 2020 23:05:46 +0200 Message-ID: Subject: Re: [PATCH] kasan: Disable branch tracing for core runtime To: Marco Elver Cc: Dmitry Vyukov , Alexander Potapenko , LKML , kasan-dev , Andrey Ryabinin , Andrew Morton , Linux Memory Management List , kernel test robot Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 19, 2020 at 8:25 PM Marco Elver wrote: > > During early boot, while KASAN is not yet initialized, it is possible to > enter reporting code-path and end up in kasan_report(). While > uninitialized, the branch there prevents generating any reports, > however, under certain circumstances when branches are being traced > (TRACE_BRANCH_PROFILING), we may recurse deep enough to cause kernel > reboots without warning. > > To prevent similar issues in future, we should disable branch tracing > for the core runtime. > > Link: https://lore.kernel.org/lkml/20200517011732.GE24705@shao2-debian/ > Reported-by: kernel test robot > Signed-off-by: Marco Elver > --- > mm/kasan/Makefile | 16 ++++++++-------- > mm/kasan/generic.c | 1 - > 2 files changed, 8 insertions(+), 9 deletions(-) > > diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile > index 434d503a6525..de3121848ddf 100644 > --- a/mm/kasan/Makefile > +++ b/mm/kasan/Makefile > @@ -15,14 +15,14 @@ CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE) > > # Function splitter causes unnecessary splits in __asan_load1/__asan_store1 > # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533 > -CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > -CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) > +CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > +CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING > > obj-$(CONFIG_KASAN) := common.o init.o report.o > obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > index 56ff8885fe2e..098a7dbaced6 100644 > --- a/mm/kasan/generic.c > +++ b/mm/kasan/generic.c > @@ -15,7 +15,6 @@ > */ > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > -#define DISABLE_BRANCH_PROFILING > > #include > #include > -- > 2.26.2.761.g0e0b3e54be-goog > Reviewed-by: Andrey Konovalov Thanks!