From patchwork Tue Jul 11 14:16:29 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 107383 Delivered-To: patch@linaro.org Received: by 10.140.101.44 with SMTP id t41csp4935698qge; Tue, 11 Jul 2017 07:17:48 -0700 (PDT) X-Received: by 10.98.7.204 with SMTP id 73mr42096838pfh.110.1499782667914; Tue, 11 Jul 2017 07:17:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1499782667; cv=none; d=google.com; s=arc-20160816; b=A9GcaD71XzGBXaf+YQx23rTdyJ52KVzcmknHxobaMf81w0rjMYlCqLtwjYExuU/e2C LGWDYKhEsuF3V75qt6rbE+1xn8jIpCgNJbDRvePqlLIaW1O42d+U9blaVVXBeJiKQA4M YBxRyMSqEGp6WGd86/F3Y1UrzWJodokMneY/8FT9fOXxJvAQZBhXiqnS5nZ5Xp9Fsl91 3rib/HD9vNnC4iJ/Lh7ME4s4ylyNgcndNf+zcW+zl4w2/BxkluV3GQZsGuGHWdqE3sB9 5mHa7qmCpGEBBlj/Ebqh/W6pl6s+5yQ7mC3nuo6lxNrAIa/5aYax4L4nDvl37C8/w1PZ 6FUw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=Zfzrv8k11C88oq/PVVBt+HLhGeMBldIEGAlh0ks3jOk=; b=V/QikxwcfJ3hWbq1sPfvzv88AEdcxt79U9FaCBErT9300kLxiNGj1M1bFrXYMth4K8 3r2eD8QXGmHh7kmPVcV5ASUIVba44xtPIuJphPNI92PJc+SfT0MBIZgYibXmMCP4Mk96 nk60sTUqBzdVflTpw+6xGYFBb9tqI/vT5cquTyGEdICXeWGLqNnEbyY0sKb3NAS1H+Wz S1rXSU0jA4b19p+MMrjLNwlpTwytow664sY7KbFQNSTncrBX7TsJZQLNs382CjUvrD6d VkVdTIaNTkHXK8EtwHHRWm4CxthBxDHTIChpBZRsl2kwz8tZr9dx4hINQGUvr9A5hj3H i3nA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y22si55358pli.164.2017.07.11.07.17.47; Tue, 11 Jul 2017 07:17:47 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932863AbdGKORq (ORCPT + 25 others); Tue, 11 Jul 2017 10:17:46 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:45434 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932837AbdGKORn (ORCPT ); Tue, 11 Jul 2017 10:17:43 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 54AA815AD; Tue, 11 Jul 2017 07:17:42 -0700 (PDT) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 388AD3F3E1; Tue, 11 Jul 2017 07:17:40 -0700 (PDT) From: Mark Rutland To: linux-arm-kerne@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Cc: catalin.marinas@arm.com, james.morse@arm.com, labbott@redhat.com, linux@armlinux.org.uk, mark.rutland@arm.com, stable@vger.kernel.org, steve.capper@arm.com, will.deacon@arm.com, viro@zeniv.linux.org.uk, peterz@infradead.org, luto@amacapital.net Subject: [PATCH 1/2] arm64: mm: abort uaccess retries upon fatal signal Date: Tue, 11 Jul 2017 15:16:29 +0100 Message-Id: <1499782590-31366-2-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1499782590-31366-1-git-send-email-mark.rutland@arm.com> References: <1499782590-31366-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When there's a fatal signal pending, arm64's do_page_fault() implementation returns 0. The intent is that we'll return to the faulting userspace instruction, delivering the signal on the way. However, if we take a fatal signal during fixing up a uaccess, this results in a return to the faulting kernel instruction, which will be instantly retried, resulting in the same fault being taken forever. As the task never reaches userspace, the signal is not delivered, and the task is left unkillable. While the task is stuck in this state, it can inhibit the forward progress of the system. To avoid this, we must ensure that when a fatal signal is pending, we apply any necessary fixup for a faulting kernel instruction. Thus we will return to an error path, and it is up to that code to make forward progress towards delivering the fatal signal. Signed-off-by: Mark Rutland Reviewed-by: Steve Capper Tested-by: Steve Capper Cc: Catalin Marinas Cc: James Morse Cc: Laura Abbott Cc: Will Deacon Cc: stable@vger.kernel.org --- arch/arm64/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) -- 1.9.1 diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 37b95df..3952d5e 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -397,8 +397,11 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, * signal first. We do not need to release the mmap_sem because it * would already be released in __lock_page_or_retry in mm/filemap.c. */ - if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { + if (!user_mode(regs)) + goto no_context; return 0; + } /* * Major/minor page fault accounting is only done on the initial From patchwork Tue Jul 11 14:16:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 107384 Delivered-To: patch@linaro.org Received: by 10.140.101.44 with SMTP id t41csp4935790qge; Tue, 11 Jul 2017 07:17:53 -0700 (PDT) X-Received: by 10.84.216.26 with SMTP id m26mr173456pli.112.1499782673154; Tue, 11 Jul 2017 07:17:53 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1499782673; cv=none; d=google.com; s=arc-20160816; b=sPlxpMmetezpkzcg7OjuXfPIMT9ik65DBWnyPFiC9Wh94MvgjhwO8AZAmFCcWk1i05 IF/ceFoiSz+6A2reGwdhHL2HDuyQ7xLDk75engO0nzqFTjpKVeZSITm68m5ep/m7tr21 74isIRTGSvNiimXBQLpNy62+NXsSZ4E4tJWYAUkVEVjPLBdiO6mbstsIP4aDffvbWHvu PWWBb/SvAwAdzJz8B2kuxiK0goPFTIBuTtZwZsmpwHVONlbWnoO+et8b2qAcA7/0cvS4 oYy0LJ7r6tSs+9APJlsd/3BoFt71/Rxne2WaJX73cqeFqRaNXFpo+lZFivP2/JWGd/5u Ydog== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=6MpXiAn1Nb7JxtJ1x+an2BJqVEk4uqT9RXapDBXn/U0=; b=YEgMoaqGq/epHDUNUSknfGRp0y++EfoIpFWnZcFs/PkSNcD7Crm9kXW0ElKtlgrc/M XvyoSz25Kgn4xBM9q8iK0WGWWIlCxM+zGABvsS4wADr6KEC2mdZdzJ25irNj4bbUbFwY lCH1regPwSY1jjUURHcq+LX+UcUJeRvXvohztcb6q4FYtg7KbYISyFGrGFvUZlph9hcH kDp/kvJ3bt5Oiz5flVH05DlozJCMzYA5iGUvT4PYBcswEKgiQcjr1nluFeyVYufOE58D r+LiOk1O6tN8bc1qkSm+LdSes2iF7NIiAeAQKLsTTy5IJFPgetaHcQmBp+VQNpK5M2uP 2NOw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 71si49050pfo.179.2017.07.11.07.17.52; Tue, 11 Jul 2017 07:17:53 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932886AbdGKORt (ORCPT + 25 others); Tue, 11 Jul 2017 10:17:49 -0400 Received: from foss.arm.com ([217.140.101.70]:45450 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932837AbdGKORq (ORCPT ); Tue, 11 Jul 2017 10:17:46 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F1F661610; Tue, 11 Jul 2017 07:17:45 -0700 (PDT) Received: from leverpostej.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D759E3F3E1; Tue, 11 Jul 2017 07:17:43 -0700 (PDT) From: Mark Rutland To: linux-arm-kerne@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Russell King Cc: catalin.marinas@arm.com, james.morse@arm.com, labbott@redhat.com, mark.rutland@arm.com, stable@vger.kernel.org, steve.capper@arm.com, will.deacon@arm.com, viro@zeniv.linux.org.uk, peterz@infradead.org, luto@amacapital.net Subject: [PATCH 2/2] arm: mm: abort uaccess retries upon fatal signal Date: Tue, 11 Jul 2017 15:16:30 +0100 Message-Id: <1499782590-31366-3-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1499782590-31366-1-git-send-email-mark.rutland@arm.com> References: <1499782590-31366-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When there's a fatal signal pending, arm's do_page_fault() implementation returns 0. The intent is that we'll return to the faulting userspace instruction, delivering the signal on the way. However, if we take a fatal signal during fixing up a uaccess, this results in a return to the faulting kernel instruction, which will be instantly retried, resulting in the same fault being taken forever. As the task never reaches userspace, the signal is not delivered, and the task is left unkillable. While the task is stuck in this state, it can inhibit the forward progress of the system. To avoid this, we must ensure that when a fatal signal is pending, we apply any necessary fixup for a faulting kernel instruction. Thus we will return to an error path, and it is up to that code to make forward progress towards delivering the fatal signal. Signed-off-by: Mark Rutland Reviewed-by: Steve Capper Cc: Russell King Cc: stable@vger.kernel.org --- arch/arm/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) -- 1.9.1 diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index ff8b0aa..42f5853 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -315,8 +315,11 @@ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma) * signal first. We do not need to release the mmap_sem because * it would already be released in __lock_page_or_retry in * mm/filemap.c. */ - if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { + if (!user_mode(regs)) + goto no_context; return 0; + } /* * Major/minor page fault accounting is only done on the