From nobody Fri Dec 19 20:34:49 2025 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 97B22C6FA89 for ; Thu, 15 Sep 2022 15:10:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230507AbiIOPKt (ORCPT ); Thu, 15 Sep 2022 11:10:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48724 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230434AbiIOPJB (ORCPT ); Thu, 15 Sep 2022 11:09:01 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86DA398C97 for ; Thu, 15 Sep 2022 08:06:03 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 201-20020a2505d2000000b006a941934651so16170353ybf.13 for ; Thu, 15 Sep 2022 08:06:03 -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; bh=mxKrKakNES2O6WNVUjUiVAG/aqg8NEyyXmfzwvDy3M8=; b=QcWSJZZkiYWs+sa+cokZ+5ih/3AigYwqha5oBzQKZX2ROZg6ZA3IUEgOs0eaSXO+su nynwTZxRJ3h5UK5bRt9ZIBKugOR9VD/wb2UQjdtResQ/B8p8IkXP6aGpAvmpsNj4uPDT g9XcO9t+eEd46cZjKpaZdtoo+KHYDdMPK4LApETzHxHqBUgFU1YKU7DIXGAmDZ5uwQk1 VZTeF44KqcNIcSibzQDkTi6BRiZq+KBK3WRtjsxy+OtraDYZ7O7tuXbkHApnF4hjaeSB xkP3yPUIvRQJsGMky0kNRvZS+Rc0renoCDGlUJjq1GKjAS9Q6aHVUEG99/PfpTuNweGG CY+w== 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; bh=mxKrKakNES2O6WNVUjUiVAG/aqg8NEyyXmfzwvDy3M8=; b=tF7zluVIX0yiQJEOagb+9Lz+H7HQAR7ra2Xp5bDcOTpxU3P9kyAyxfjhSQeKjPvdKt gb0zWnX1pXmYo90K+12fFZll2hCC/5ch3qsOQm+1kPf47fv7GZh03kz0BxKW2WoGntKK fld1Ds/oWrOsU0YTW7RpQoFJ+M30XN/Edq+bWRGxCz6hTTiKgu7vwrLaZKMLzgxyNHuW aaeLXTSJ37SwDP2gdiQLlsycPuiADzs+/l/S0K88FLW5OVJzQk4TGDk6ZNi2qbX+YmhA 5Wti1hEoiVTPC7cZRFRya1HZNv38JKhNvgHR73EQr8Iu1f8QiRmbv3gCd4kKQ8Famdwn Ow0w== X-Gm-Message-State: ACrzQf1RY7xMcfTfEp58GAU2bg6VxeKNKP2HwVR68ak4HJSNokyNDUXK 5VDT4c/rSb1CNrVLQhXrMCjviCzdtLs= X-Google-Smtp-Source: AMsMyM5QNy6iagLQZF5XlPAvUcWfp+eaYBogp+9cAeIdO1aa1vANNHLNyhp7U4YSK9OGDcBNDqZffj+MYXA= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:686d:27b5:495:85b7]) (user=glider job=sendgmr) by 2002:a81:a503:0:b0:349:f6c6:434 with SMTP id u3-20020a81a503000000b00349f6c60434mr248211ywg.70.1663254362758; Thu, 15 Sep 2022 08:06:02 -0700 (PDT) Date: Thu, 15 Sep 2022 17:04:05 +0200 In-Reply-To: <20220915150417.722975-1-glider@google.com> Mime-Version: 1.0 References: <20220915150417.722975-1-glider@google.com> X-Mailer: git-send-email 2.37.2.789.g6183377224-goog Message-ID: <20220915150417.722975-32-glider@google.com> Subject: [PATCH v7 31/43] objtool: kmsan: list KMSAN API functions as uaccess-safe From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Alexei Starovoitov , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Biggers , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Stephen Rothwell , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" KMSAN inserts API function calls in a lot of places (function entries and exits, local variables, memory accesses), so they may get called from the uaccess regions as well. KMSAN API functions are used to update the metadata (shadow/origin pages) for kernel memory accesses. The metadata pages for kernel pointers are also located in the kernel memory, so touching them is not a problem. For userspace pointers, no metadata is allocated. If an API function is supposed to read or modify the metadata, it does so for kernel pointers and ignores userspace pointers. If an API function is supposed to return a pair of metadata pointers for the instrumentation to use (like all __msan_metadata_ptr_for_TYPE_SIZE() functions do), it returns the allocated metadata for kernel pointers and special dummy buffers residing in the kernel memory for userspace pointers. As a result, none of KMSAN API functions perform userspace accesses, but since they might be called from UACCESS regions they use user_access_save/restore(). Signed-off-by: Alexander Potapenko --- v3: -- updated the patch description v4: -- add kmsan_unpoison_entry_regs() Link: https://linux-review.googlesource.com/id/I242bc9816273fecad4ea3d97739= 3784396bb3c35 --- tools/objtool/check.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e55fdf952a3a1..7c048c11ce7da 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1062,6 +1062,26 @@ static const char *uaccess_safe_builtin[] =3D { "__sanitizer_cov_trace_cmp4", "__sanitizer_cov_trace_cmp8", "__sanitizer_cov_trace_switch", + /* KMSAN */ + "kmsan_copy_to_user", + "kmsan_report", + "kmsan_unpoison_entry_regs", + "kmsan_unpoison_memory", + "__msan_chain_origin", + "__msan_get_context_state", + "__msan_instrument_asm_store", + "__msan_metadata_ptr_for_load_1", + "__msan_metadata_ptr_for_load_2", + "__msan_metadata_ptr_for_load_4", + "__msan_metadata_ptr_for_load_8", + "__msan_metadata_ptr_for_load_n", + "__msan_metadata_ptr_for_store_1", + "__msan_metadata_ptr_for_store_2", + "__msan_metadata_ptr_for_store_4", + "__msan_metadata_ptr_for_store_8", + "__msan_metadata_ptr_for_store_n", + "__msan_poison_alloca", + "__msan_warning", /* UBSAN */ "ubsan_type_mismatch_common", "__ubsan_handle_type_mismatch", --=20 2.37.2.789.g6183377224-goog