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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72F88C433F5 for ; Wed, 29 Sep 2021 10:30:07 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3D276613A5 for ; Wed, 29 Sep 2021 10:30:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3D276613A5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:CC:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; 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Wed, 29 Sep 2021 03:28:06 -0700 Received: from mtkmbs07n1.mediatek.inc (172.21.101.16) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 29 Sep 2021 03:28:04 -0700 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs07n1.mediatek.inc (172.21.101.16) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 29 Sep 2021 18:28:03 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 29 Sep 2021 18:28:03 +0800 Message-ID: <1c8464602db6ded259859e7d5866381017d953f3.camel@mediatek.com> Subject: Re: [PATCH] scs: Release kasan vmalloc poison in scs_free process From: Kuan-Ying Lee To: Sami Tolvanen CC: , LKML , , , Matthias Brugger , Will Deacon , "moderated list:ARM/Mediatek SoC support" , "moderated list:ARM/Mediatek SoC support" , Date: Wed, 29 Sep 2021 18:28:03 +0800 In-Reply-To: References: <20210923095316.13867-1-yee.lee@mediatek.com> <5f7a9ed1dabba25596c38a8e7c32ee5750b80459.camel@mediatek.com> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210929_032814_940058_CB184054 X-CRM114-Status: GOOD ( 28.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 2021-09-24 at 07:35 -0700, Sami Tolvanen wrote: > On Thu, Sep 23, 2021 at 4:19 AM Kuan-Ying Lee > wrote: > > > > On Thu, 2021-09-23 at 17:53 +0800, yee.lee@mediatek.com wrote: > > > From: Yee Lee > > > > > > Since scs allocation has been moved to vmalloc region, the > > > shadow stack is protected by kasan_posion_vmalloc. > > > However, the vfree_atomic operation needs to access > > > its context for scs_free process and causes kasan error > > > as the dump info below. > > > > > > This patch Adds kasan_unpoison_vmalloc() before vfree_atomic, > > > which aligns to the prior flow as using kmem_cache. > > > The vmalloc region will go back posioned in the following > > > vumap() operations. > > > > > > ================================================================ > > > == > > > BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4 > > > Write of size 8 at addr ffff8000100b9000 by task kthreadd/2 > > > > > > CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-(skip) > > > Hardware name: linux,dummy-virt (DT) > > > Call trace: > > > dump_backtrace+0x0/0x43c > > > show_stack+0x1c/0x2c > > > dump_stack_lvl+0x68/0x84 > > > print_address_description+0x80/0x394 > > > kasan_report+0x180/0x1dc > > > __asan_report_store8_noabort+0x48/0x58 > > > llist_add_batch+0x60/0xd4 > > > vfree_atomic+0x60/0xe0 > > > scs_free+0x1dc/0x1fc > > > scs_release+0xa4/0xd4 > > > free_task+0x30/0xe4 > > > __put_task_struct+0x1ec/0x2e0 > > > delayed_put_task_struct+0x5c/0xa0 > > > rcu_do_batch+0x62c/0x8a0 > > > rcu_core+0x60c/0xc14 > > > rcu_core_si+0x14/0x24 > > > __do_softirq+0x19c/0x68c > > > irq_exit+0x118/0x2dc > > > handle_domain_irq+0xcc/0x134 > > > gic_handle_irq+0x7c/0x1bc > > > call_on_irq_stack+0x40/0x70 > > > do_interrupt_handler+0x78/0x9c > > > el1_interrupt+0x34/0x60 > > > el1h_64_irq_handler+0x1c/0x2c > > > el1h_64_irq+0x78/0x7c > > > _raw_spin_unlock_irqrestore+0x40/0xcc > > > sched_fork+0x4f0/0xb00 > > > copy_process+0xacc/0x3648 > > > kernel_clone+0x168/0x534 > > > kernel_thread+0x13c/0x1b0 > > > kthreadd+0x2bc/0x400 > > > ret_from_fork+0x10/0x20 > > > > > > Memory state around the buggy address: > > > ffff8000100b8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > > > f8 > > > ffff8000100b8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > > > f8 > > > >ffff8000100b9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > > > f8 > > > ^ > > > ffff8000100b9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > > > f8 > > > ffff8000100b9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > > > f8 > > > ================================================================ > > > == > > > > > > CC: Matthias Brugger > > > CC: Will Deacon > > > CC: Sami Tolvanen > > > Signed-off-by: Yee Lee > > > --- > > > kernel/scs.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/kernel/scs.c b/kernel/scs.c > > > index e2a71fc82fa0..25c0d8e416e6 100644 > > > --- a/kernel/scs.c > > > +++ b/kernel/scs.c > > > @@ -68,6 +68,7 @@ void scs_free(void *s) > > > > > > __scs_account(s, -1); > > > > > > + kasan_unpoison_vmalloc(s, SCS_SIZE); > > > /* > > > * We cannot sleep as this can be called in interrupt > > > context, > > > * so use this_cpu_cmpxchg to update the cache, and > > > vfree_atomic > > > > I'm not sure if we need to add kasan_unpoison_vmalloc() and > > kasan_poison_vmalloc() in this file. > > > > As far as I know, vmalloc() and vfree() will do these two > > functions. > > The idea here is to poison the shadow stack after it's set up to > catch > unintentional accesses. Outside of compiler instrumentation, nothing > should read or write from this buffer while the task is running. Got it. Thanks. Reviewed-by: Kuan-Ying Lee > > Sami _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel