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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7A8BC433FE for ; Wed, 2 Nov 2022 11:06:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230408AbiKBLGl (ORCPT ); Wed, 2 Nov 2022 07:06:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230342AbiKBLGd (ORCPT ); Wed, 2 Nov 2022 07:06:33 -0400 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70F9029C9A for ; Wed, 2 Nov 2022 04:06:28 -0700 (PDT) Received: by mail-ed1-x549.google.com with SMTP id v18-20020a056402349200b004622e273bbbso11777352edc.14 for ; Wed, 02 Nov 2022 04:06:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Dk/dhHPL0qFVshysQ/N4gnrAp81kLluhRpZpiN1N26A=; b=BRXuAvLOHF3g9+gYxk6eLf0iLGvj05paMev0jUBgMnN/5twd8iGLllzv5YJfGiXvxo bbpa22yuLIs03sydQwA6d6FHWh1ns4oA9GlUYXwh/RQbSpseclTQoxYM356MlrCxyM/d l7xAksNUDe2qS9tRUGAgfy+pCWc4utGI5Aty2dyjLc/3QuuQjIB0MOtKWoWhtakZ6Yli rzVdmRwM0RTjlvJ/Zf6eD8WP9SwZrTA2aldlm9B/FxucwGXrXuxw2IjQDm4QRRrggsYe oNPE1SV5IP9wsvvEx/aHSu69q3tQhoACudVb+Jy9nLyKvCVO3Fknl0VsdVPh0u+lG1Ta aVsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Dk/dhHPL0qFVshysQ/N4gnrAp81kLluhRpZpiN1N26A=; b=TElqPd5Npt1rUPN5Kuxr5T9TD7OkEcegoxFibIKREEkDY2W7Z0t4It0QBf5R1Lh0Z2 MhQdqeWKgAvu7+xaNvOxgMTWKqGQL1Mw+jwgpTB9I2N9YhLbFKhXaPiGUAWTPI3ZGMyS qf2864yDg5RmM3mbdbxNDRRq50PE7MuVv4L1AqMhD4dKta7we73OmOaEGzmpNwguxNJC ydKxI7ic5eQrv89bA9b9kOLshPo0bLUqJFAOdjyGykXNQcGU8mxQ+k0K1oAnGzsYemEJ pLqitAOZLnUDbkDw3KoquEnZYkhhQE8Cx+GbvwaYZc0LULx4PLqmkBLPYYOtWt99rzwB /lwA== X-Gm-Message-State: ACrzQf1dlAUOmR9kWRWL0ZKHMgy1Pb336soJoPpSWCJiKh2xU3Wn4fjx FQfUnrpZs+GNAZrJLQzhoZ/PDUmQAIM= X-Google-Smtp-Source: AMsMyM4fUfxUdb/RWuOeQOt7gjfxrb6bfUNzqz8xTAK3dw9fr/vhi9KtZr6+Qf+4LF3jQ4Jn/CWpERzPtqA= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:7f41:af20:8:a96d]) (user=glider job=sendgmr) by 2002:a17:907:a80f:b0:7ae:3f7:b612 with SMTP id vo15-20020a170907a80f00b007ae03f7b612mr2514087ejc.421.1667387186488; Wed, 02 Nov 2022 04:06:26 -0700 (PDT) Date: Wed, 2 Nov 2022 12:06:11 +0100 In-Reply-To: <20221102110611.1085175-1-glider@google.com> Mime-Version: 1.0 References: <20221102110611.1085175-1-glider@google.com> X-Mailer: git-send-email 2.38.1.273.g43a17bfeac-goog Message-ID: <20221102110611.1085175-5-glider@google.com> Subject: [PATCH 5/5] x86/traps: avoid KMSAN bugs originating from handle_bug() From: Alexander Potapenko To: glider@google.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Borislav Petkov , Dave Hansen , Ingo Molnar , Thomas Gleixner , x86@kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a case in exc_invalid_op handler that is executed outside the irqentry_enter()/irqentry_exit() region when an UD2 instruction is used to encode a call to __warn(). In that case the `struct pt_regs` passed to the interrupt handler is never unpoisoned by KMSAN (this is normally done in irqentry_enter()), which leads to false positives inside handle_bug(). Use kmsan_unpoison_entry_regs() to explicitly unpoison those registers before using them. Cc: Andrew Morton Cc: Borislav Petkov Cc: Dave Hansen Cc: Ingo Molnar Cc: Thomas Gleixner Cc: x86@kernel.org Signed-off-by: Alexander Potapenko --- arch/x86/kernel/traps.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 178015a820f08..d3fdec706f1d2 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -301,6 +302,12 @@ static noinstr bool handle_bug(struct pt_regs *regs) { bool handled = false; + /* + * Normally @regs are unpoisoned by irqentry_enter(), but handle_bug() + * is a rare case that uses @regs without passing them to + * irqentry_enter(). + */ + kmsan_unpoison_entry_regs(regs); if (!is_valid_bugaddr(regs->ip)) return handled; -- 2.38.1.273.g43a17bfeac-goog