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 CC15FC43217 for ; Mon, 3 Oct 2022 21:15:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229588AbiJCVPL (ORCPT ); Mon, 3 Oct 2022 17:15:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230255AbiJCVNw (ORCPT ); Mon, 3 Oct 2022 17:13:52 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CEE9A54667 for ; Mon, 3 Oct 2022 14:09:00 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1D14AB81123 for ; Mon, 3 Oct 2022 21:08:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3C8CC433C1; Mon, 3 Oct 2022 21:08:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1664831337; bh=fdMvwgGnM0OAMBh6+N0bvaRiaiqbkPoDarUreRPNfNs=; h=Date:To:From:Subject:From; b=mB6OvdnP+xPgIJqVPNTbwCrrnjUM5UG0GaHe+dOXbYJ1kAxwMna79H03JwjY4r2yj DKrlx4vhd1hxUhKzz4C6hdNcUn9o9c7x+6VCXsdbtcqgehXuAjg/zQw7UG8WHCYAfa 9V6vbUPCzUfQJITR3EfSD05nUu9klkt/0QPo0H0k= Date: Mon, 03 Oct 2022 14:08:57 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, viro@zeniv.linux.org.uk, vegard.nossum@oracle.com, vbabka@suse.cz, tglx@linutronix.de, sfr@canb.auug.org.au, rostedt@goodmis.org, rientjes@google.com, pmladek@suse.com, peterz@infradead.org, penberg@kernel.org, mst@redhat.com, mingo@redhat.com, mark.rutland@arm.com, luto@kernel.org, keescook@chromium.org, iii@linux.ibm.com, iamjoonsoo.kim@lge.com, herbert@gondor.apana.org.au, hch@lst.de, gregkh@linuxfoundation.org, gor@linux.ibm.com, elver@google.com, edumazet@google.com, ebiggers@kernel.org, ebiggers@google.com, dvyukov@google.com, cl@linux.com, bp@alien8.de, axboe@kernel.dk, ast@kernel.org, arnd@arndb.de, andreyknvl@google.com, andreyknvl@gmail.com, glider@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] x86-kmsan-skip-shadow-checks-in-__switch_to.patch removed from -mm tree Message-Id: <20221003210857.C3C8CC433C1@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: x86: kmsan: skip shadow checks in __switch_to() has been removed from the -mm tree. Its filename was x86-kmsan-skip-shadow-checks-in-__switch_to.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Alexander Potapenko Subject: x86: kmsan: skip shadow checks in __switch_to() Date: Thu, 15 Sep 2022 17:04:07 +0200 When instrumenting functions, KMSAN obtains the per-task state (mostly pointers to metadata for function arguments and return values) once per function at its beginning, using the `current` pointer. Every time the instrumented function calls another function, this state (`struct kmsan_context_state`) is updated with shadow/origin data of the passed and returned values. When `current` changes in the low-level arch code, instrumented code can not notice that, and will still refer to the old state, possibly corrupting it or using stale data. This may result in false positive reports. To deal with that, we need to apply __no_kmsan_checks to the functions performing context switching - this will result in skipping all KMSAN shadow checks and marking newly created values as initialized, preventing all false positive reports in those functions. False negatives are still possible, but we expect them to be rare and impersistent. Link: https://lkml.kernel.org/r/20220915150417.722975-34-glider@google.com Suggested-by: Marco Elver Signed-off-by: Alexander Potapenko Cc: Alexander Viro Cc: Alexei Starovoitov Cc: Andrey Konovalov Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christoph Hellwig Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Eric Biggers Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Ilya Leoshkevich Cc: Ingo Molnar Cc: Jens Axboe Cc: Joonsoo Kim Cc: Kees Cook Cc: Mark Rutland Cc: Matthew Wilcox Cc: Michael S. Tsirkin Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Petr Mladek Cc: Stephen Rothwell Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vegard Nossum Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- arch/x86/kernel/process_64.c | 1 + 1 file changed, 1 insertion(+) --- a/arch/x86/kernel/process_64.c~x86-kmsan-skip-shadow-checks-in-__switch_to +++ a/arch/x86/kernel/process_64.c @@ -553,6 +553,7 @@ void compat_start_thread(struct pt_regs * Kprobes not supported here. Set the probe on schedule instead. * Function graph tracer not supported too. */ +__no_kmsan_checks __visible __notrace_funcgraph struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) { _ Patches currently in -mm which might be from glider@google.com are