From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.101.70]:60942 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727079AbfCRLrY (ORCPT ); Mon, 18 Mar 2019 07:47:24 -0400 Subject: Re: [PATCH v11 09/14] kernel, arm64: untag user pointers in prctl_set_mm* References: From: Kevin Brodsky Message-ID: <96675b72-d325-0682-4864-b6a96f63f8fd@arm.com> Date: Mon, 18 Mar 2019 11:47:15 +0000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-GB Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrey Konovalov , Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Szabolcs Nagy On 15/03/2019 19:51, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > prctl_set_mm() and prctl_set_mm_map() use provided user pointers for vma > lookups, which can only by done with untagged pointers. > > Untag user pointers in these functions. > > Signed-off-by: Andrey Konovalov > --- > kernel/sys.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/kernel/sys.c b/kernel/sys.c > index 12df0e5434b8..8e56d87cc6db 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -1993,6 +1993,18 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data > if (copy_from_user(&prctl_map, addr, sizeof(prctl_map))) > return -EFAULT; > > + prctl_map->start_code = untagged_addr(prctl_map.start_code); > + prctl_map->end_code = untagged_addr(prctl_map.end_code); > + prctl_map->start_data = untagged_addr(prctl_map.start_data); > + prctl_map->end_data = untagged_addr(prctl_map.end_data); > + prctl_map->start_brk = untagged_addr(prctl_map.start_brk); > + prctl_map->brk = untagged_addr(prctl_map.brk); > + prctl_map->start_stack = untagged_addr(prctl_map.start_stack); > + prctl_map->arg_start = untagged_addr(prctl_map.arg_start); > + prctl_map->arg_end = untagged_addr(prctl_map.arg_end); > + prctl_map->env_start = untagged_addr(prctl_map.env_start); > + prctl_map->env_end = untagged_addr(prctl_map.env_end); As the buildbot suggests, those -> should be . instead :) You might want to check your local build with CONFIG_CHECKPOINT_RESTORE=y. > + > error = validate_prctl_map(&prctl_map); > if (error) > return error; > @@ -2106,6 +2118,8 @@ static int prctl_set_mm(int opt, unsigned long addr, > opt != PR_SET_MM_MAP_SIZE))) > return -EINVAL; > > + addr = untagged_addr(addr); This is a bit too coarse, addr is indeed used for find_vma() later on, but it is also used to access memory, by prctl_set_mm_mmap() and prctl_set_auxv(). Kevin > + > #ifdef CONFIG_CHECKPOINT_RESTORE > if (opt == PR_SET_MM_MAP || opt == PR_SET_MM_MAP_SIZE) > return prctl_set_mm_map(opt, (const void __user *)addr, arg4);