From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 632EC6B0007 for ; Thu, 8 Feb 2018 11:30:46 -0500 (EST) Received: by mail-qt0-f197.google.com with SMTP id d15so4163785qtg.2 for ; Thu, 08 Feb 2018 08:30:46 -0800 (PST) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id h2si279870qkc.74.2018.02.08.08.30.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 08 Feb 2018 08:30:45 -0800 (PST) Date: Thu, 8 Feb 2018 10:30:41 -0600 From: Josh Poimboeuf Subject: Re: [PATCH RFC] x86: KASAN: Sanitize unauthorized irq stack access Message-ID: <20180208163041.zy7dbz4tlbit4i2h@treble> References: <151802005995.4570.824586713429099710.stgit@localhost.localdomain> <6638b09b-30b0-861e-9c00-c294889a3791@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Kirill Tkhai Cc: Dave Hansen , tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, aryabinin@virtuozzo.com, glider@google.com, dvyukov@google.com, luto@kernel.org, bp@alien8.de, jgross@suse.com, kirill.shutemov@linux.intel.com, keescook@chromium.org, minipli@googlemail.com, gregkh@linuxfoundation.org, kstewart@linuxfoundation.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org On Thu, Feb 08, 2018 at 01:03:49PM +0300, Kirill Tkhai wrote: > On 07.02.2018 21:38, Dave Hansen wrote: > > On 02/07/2018 08:14 AM, Kirill Tkhai wrote: > >> Sometimes it is possible to meet a situation, > >> when irq stack is corrupted, while innocent > >> callback function is being executed. This may > >> happen because of crappy drivers irq handlers, > >> when they access wrong memory on the irq stack. > > > > Can you be more clear about the actual issue? Which drivers do this? > > How do they even find an IRQ stack pointer? > > I can't say actual driver making this, because I'm still investigating the guilty one. > But I have couple of crash dumps with the crash inside update_sd_lb_stats() function, > where stack variable sg becomes corrupted. This time all scheduler-related not-stack > variables are in ideal state. And update_sd_lb_stats() is the function, which can't > corrupt its own stack. So, I thought this functionality may be useful for something else, > especially because of irq stack is one of the last stacks, which are not sanitized. > Task's stacks are already covered, as I know > > [1595450.678971] Call Trace: > [1595450.683991] > [1595450.684038] > [1595450.688926] [] cpumask_next_and+0x35/0x50 > [1595450.693984] [] find_busiest_group+0x143/0x950 > [1595450.699088] [] load_balance+0x19a/0xc20 > [1595450.704289] [] ? sched_clock_cpu+0x85/0xc0 > [1595450.709457] [] ? update_rq_clock.part.88+0x1a/0x150 > [1595450.714711] [] rebalance_domains+0x170/0x2b0 > [1595450.719997] [] run_rebalance_domains+0x122/0x1e0 > [1595450.725321] [] __do_softirq+0x10f/0x2aa > [1595450.730746] [] call_softirq+0x1c/0x30 > [1595450.736169] [] do_softirq+0x65/0xa0 > [1595450.741754] [] irq_exit+0x105/0x110 > [1595450.747279] [] smp_apic_timer_interrupt+0x42/0x50 > [1595450.752905] [] apic_timer_interrupt+0x232/0x240 > [1595450.758519] > [1595450.758569] > [1595450.764100] [] ? cpuidle_enter_state+0x52/0xc0 > [1595450.769652] [] cpuidle_idle_call+0xd8/0x210 > [1595450.775198] [] arch_cpu_idle+0xe/0x30 > [1595450.780813] [] cpu_startup_entry+0x14a/0x1c0 > [1595450.786286] [] start_secondary+0x1d6/0x250 I'm not seeing how this patch would help. If you're running on the irq stack, the *entire* irq stack would be unpoisoned. So there's still no KASAN protection. Or am I missing something? Seems like it would be more useful for KASAN to detect redzone accesses on the irq stack (if it's not doing that already). -- Josh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org