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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4254C433EF for ; Fri, 6 May 2022 16:14:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ED8D36B0072; Fri, 6 May 2022 12:14:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E88E56B0073; Fri, 6 May 2022 12:14:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D299A6B0074; Fri, 6 May 2022 12:14:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0109.hostedemail.com [216.40.44.109]) by kanga.kvack.org (Postfix) with ESMTP id C3F676B0072 for ; Fri, 6 May 2022 12:14:40 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 82BD2184F16E7 for ; Fri, 6 May 2022 16:14:40 +0000 (UTC) X-FDA: 79435816320.27.F67A868 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf23.hostedemail.com (Postfix) with ESMTP id 20CEF140050 for ; Fri, 6 May 2022 16:14:28 +0000 (UTC) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1651853677; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eGIaI6FR4z9ZKAajKHVzAuOrHeyDOTq0yBE9J83Z0DM=; b=BP8TefPhONS8kML5NOLtpqXmzambUy0GK8jRF4v5uGIa0Q+/JF67dmyIKUFDZXdtkdgEH3 gAIhBHABcrOC2He1B7b5Y7v73xCxBS1QCOPiUZhjc5BsFx/1mQksKoyoU4EwvNH7+h4aoz Bdq07PrVDHsH6ZEYlsN/pWktW+cUEYejiG3BdFq0bzOTbDXcFeG37Hs5/mJ034JuqT7+PV 3VKnqbSUd17z9NG8jDKj3nc5kv+pcwotIX+kChEH2NIVF828gwNWslAaUqeIUokFPXDJ5d GbN2LPaEKfDIabQrU9y03/pgCGy8JVUc125APHZoRU6jo7tzc4Oq+ThteyikYQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1651853677; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eGIaI6FR4z9ZKAajKHVzAuOrHeyDOTq0yBE9J83Z0DM=; b=pcMuIo9aq1DOq5bWbaoANP7IgoaUD36hkEleH8xagaT73ZawBHhxDCvKJEKK5auc97xb+k alDKkQkLUmqNSHAQ== To: Alexander Potapenko Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , 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 , Steven Rostedt , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev , Linux Memory Management List , Linux-Arch , LKML Subject: Re: [PATCH v3 28/46] kmsan: entry: handle register passing from uninstrumented code In-Reply-To: References: <20220426164315.625149-1-glider@google.com> <20220426164315.625149-29-glider@google.com> <87a6c6y7mg.ffs@tglx> <87y1zjlhmj.ffs@tglx> <878rrfiqyr.ffs@tglx> Date: Fri, 06 May 2022 18:14:36 +0200 Message-ID: <87k0ayhc43.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=BP8TefPh; dkim=pass header.d=linutronix.de header.s=2020e header.b=pcMuIo9a; spf=pass (imf23.hostedemail.com: domain of tglx@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=tglx@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 20CEF140050 X-Stat-Signature: cm7dtfifcb8wpb5f37s6k9k65bqjabkd X-HE-Tag: 1651853668-201509 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 06 2022 at 16:52, Alexander Potapenko wrote: > On Thu, May 5, 2022 at 11:56 PM Thomas Gleixner wrote: >> @@ -452,6 +455,7 @@ irqentry_state_t noinstr irqentry_nmi_en >> rcu_nmi_enter(); >> >> instrumentation_begin(); >> + unpoison(regs); >> trace_hardirqs_off_finish(); >> ftrace_nmi_enter(); >> instrumentation_end(); >> >> As I said: 4 places :) > > These four instances still do not look sufficient. > Right now I am seeing e.g. reports with the following stack trace: > > BUG: KMSAN: uninit-value in irqtime_account_process_tick+0x255/0x580 > kernel/sched/cputime.c:382 > irqtime_account_process_tick+0x255/0x580 kernel/sched/cputime.c:382 > account_process_tick+0x98/0x450 kernel/sched/cputime.c:476 > update_process_times+0xe4/0x3e0 kernel/time/timer.c:1786 > tick_sched_handle kernel/time/tick-sched.c:243 > tick_sched_timer+0x83e/0x9e0 kernel/time/tick-sched.c:1473 > __run_hrtimer+0x518/0xe50 kernel/time/hrtimer.c:1685 > __hrtimer_run_queues kernel/time/hrtimer.c:1749 > hrtimer_interrupt+0x838/0x15a0 kernel/time/hrtimer.c:1811 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 > __sysvec_apic_timer_interrupt+0x1ae/0x680 arch/x86/kernel/apic/apic.c:1103 > sysvec_apic_timer_interrupt+0x95/0xc0 arch/x86/kernel/apic/apic.c:1097 > ... > (uninit creation stack trace is irrelevant here, because it is some > random value from the stack) > > sysvec_apic_timer_interrupt() receives struct pt_regs from > uninstrumented code, so regs can be partially uninitialized. > They are not passed down the call stack directly, but are instead > saved by set_irq_regs() in sysvec_apic_timer_interrupt() and loaded by > get_irq_regs() in tick_sched_timer(). sysvec_apic_timer_interrupt() invokes irqentry_enter() _before_ set_irq_regs() and irqentry_enter() unpoisons @reg. Confused...