From patchwork Tue Jan 31 20:03:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13123341 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 A142CC38142 for ; Tue, 31 Jan 2023 20:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231300AbjAaUDb (ORCPT ); Tue, 31 Jan 2023 15:03:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229946AbjAaUDa (ORCPT ); Tue, 31 Jan 2023 15:03:30 -0500 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [IPv6:2a03:a000:7:0:5054:ff:fe1c:15ff]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6DA047408; Tue, 31 Jan 2023 12:03:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ED6R08GbccKYIIX9kXT549IPtW4L7cqF2AXMvdmRFj4=; b=iNM2NyBX9qKzLnSjicxOotEmdb mPwBfHxw1JcxbXjAmuQzkUPkY076SeFW9sb+OEtR3wdxggD/OHl7HF+zCRhEDKyPAy7wtUQ04tVp3 8nBqtkHhKsi9Xm58VZesKGNtjv7L3mh0zN0MWsZfar40SOh3yGMBypMpwAVllpvQK7XvGiD07RbVx KLUSciQqkdXkPxJs6MuDmfTwzuqJz2o2Ds1f0vjiLr7dRyMt1d7fXghuodLsn7lPVjZV7vudP5qG0 Z6gCcHCEbZ5W/gjbvjr/2oKDctHKl/D8ra0DVYtaeptbIhqPn6qSCGk3NWvfxTtqe3xyyb6FoIWpa Zk9x+jrw==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1pMwqm-005IlR-0f; Tue, 31 Jan 2023 20:03:28 +0000 Date: Tue, 31 Jan 2023 20:03:28 +0000 From: Al Viro To: linux-arch@vger.kernel.org Cc: linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, Michal Simek , Dinh Nguyen , openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org, Linus Torvalds Subject: [PATCH 01/10] alpha: fix livelock in uaccess Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org alpha equivalent of 26178ec11ef3 "x86: mm: consolidate VM_FAULT_RETRY handling" If e.g. get_user() triggers a page fault and a fatal signal is caught, we might end up with handle_mm_fault() returning VM_FAULT_RETRY and not doing anything to page tables. In such case we must *not* return to the faulting insn - that would repeat the entire thing without making any progress; what we need instead is to treat that as failed (user) memory access. Signed-off-by: Al Viro --- arch/alpha/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c index ef427a6bdd1a..7b01ae4f3bc6 100644 --- a/arch/alpha/mm/fault.c +++ b/arch/alpha/mm/fault.c @@ -152,8 +152,11 @@ do_page_fault(unsigned long address, unsigned long mmcsr, the fault. */ fault = handle_mm_fault(vma, address, flags, regs); - if (fault_signal_pending(fault, regs)) + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; return; + } /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED)