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 X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40716C433ED for ; Thu, 22 Apr 2021 12:53:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F389D613FB for ; Thu, 22 Apr 2021 12:53:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236290AbhDVMyR (ORCPT ); Thu, 22 Apr 2021 08:54:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:45258 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230510AbhDVMyO (ORCPT ); Thu, 22 Apr 2021 08:54:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 28C6761421; Thu, 22 Apr 2021 12:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619096020; bh=QY4q0Wt0COJBeXEbp9vPIxWFGHaGiOrakwpjUWPB1aw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ibKfsQmd0KaSiH0RVUfeEnW09IXzLMfWDpJLewySDNOiLvqG0gPVlZa5aAYmhkGU5 HEpOtY8D213CFK5vGfeKWGzJGkLSEkc26M0fQ73oJfrPcE82hn2fM3rVvySu6/vwtb DzEbaA7sp4Q5qliKJpU7SqlsIRcWaOGs6vPj5XvCgNnDgU8TjiGrbi2SNOVT+/tzB/ D+VJgevS3sTAeGOETYeYn92QCNd0AlhV5LeaWymZhhmXhhlaHcX+lg0c20Rj4v7pST 46x7WpQSA2OujBNCcG95ZNbVGsmjnO+r4Vc8X+uSGQqqgou0gDBb/eiIvCNCvaOE+0 Si5khKEWxAysA== Date: Thu, 22 Apr 2021 13:53:34 +0100 From: Will Deacon To: Liam Howlett Cc: Catalin Marinas , Julien Grall , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "bpf@vger.kernel.org" Subject: Re: [PATCH 3/3] arch/arm64/kernel/traps: Use find_vma_intersection() in traps for setting si_code Message-ID: <20210422125334.GB1521@willie-the-truck> References: <20210420165001.3790670-1-Liam.Howlett@Oracle.com> <20210420165001.3790670-3-Liam.Howlett@Oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210420165001.3790670-3-Liam.Howlett@Oracle.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 20, 2021 at 04:50:13PM +0000, Liam Howlett wrote: > find_vma() will continue to search upwards until the end of the virtual > memory space. This means the si_code would almost never be set to > SEGV_MAPERR even when the address falls outside of any VMA. The result > is that the si_code is not reliable as it may or may not be set to the > correct result, depending on where the address falls in the address > space. > > Using find_vma_intersection() allows for what is intended by only > returning a VMA if it falls within the range provided, in this case a > window of 1. > > Fixes: bd35a4adc413 (arm64: Port SWP/SWPB emulation support from arm) > Signed-off-by: Liam R. Howlett > --- > arch/arm64/kernel/traps.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > index a05d34f0e82a..a44007904a64 100644 > --- a/arch/arm64/kernel/traps.c > +++ b/arch/arm64/kernel/traps.c > @@ -383,9 +383,10 @@ void force_signal_inject(int signal, int code, unsigned long address, unsigned i > void arm64_notify_segfault(unsigned long addr) > { > int code; > + unsigned long ut_addr = untagged_addr(addr); > > mmap_read_lock(current->mm); > - if (find_vma(current->mm, untagged_addr(addr)) == NULL) > + if (find_vma_intersection(current->mm, ut_addr, ut_addr + 1) == NULL) > code = SEGV_MAPERR; > else > code = SEGV_ACCERR; I'm not seeing how this addresses VM_GROWSDOWN as Catalin mentioned before. Will