From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932079AbcEMJYS (ORCPT ); Fri, 13 May 2016 05:24:18 -0400 Received: from foss.arm.com ([217.140.101.70]:35059 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751604AbcEMJYQ (ORCPT ); Fri, 13 May 2016 05:24:16 -0400 Date: Fri, 13 May 2016 10:24:20 +0100 From: Will Deacon To: Yury Norov Cc: arnd@arndb.de, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm64: fix current_thread_info()->addr_limit setup Message-ID: <20160513092419.GA13689@arm.com> References: <1463052414-29033-1-git-send-email-ynorov@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1463052414-29033-1-git-send-email-ynorov@caviumnetworks.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 12, 2016 at 02:26:54PM +0300, Yury Norov wrote: > At elf loading in flush_old_exec() in fs/exec.c, generic code sets > current_thread_info()->addr_limit to one that corresponds aarch64 value, > and ignores compat mode there as corresponding status setup happens > later on in load_elf_binary() by SET_PERSONALITY() macro. As result, > compat task has wrong addr_limit, and it may cause various bugs. > > This patch fixes it. It also fixes USER_DS macro to return different > values depending on compat at runtime. > > It was discovered during ilp32 development. See details here: > https://lkml.org/lkml/2016/5/11/975 It looks like that thread is ongoing, with discussion around a generic fix and a related issue with our TLS handling: https://lkml.org/lkml/2016/5/12/513 https://lkml.org/lkml/2016/5/12/515 so I'm going to hold off on this until there's some agreement on the right way forward. Whatever we end up doing, we should probably cc stable too. > Signed-off-by: Yury Norov > --- > arch/arm64/include/asm/elf.h | 11 +++++++++-- > arch/arm64/include/asm/uaccess.h | 2 +- > 2 files changed, 10 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h > index 24ed037..fda75ce 100644 > --- a/arch/arm64/include/asm/elf.h > +++ b/arch/arm64/include/asm/elf.h > @@ -138,7 +138,10 @@ typedef struct user_fpsimd_state elf_fpregset_t; > */ > #define ELF_PLAT_INIT(_r, load_addr) (_r)->regs[0] = 0 > > -#define SET_PERSONALITY(ex) clear_thread_flag(TIF_32BIT); > +#define SET_PERSONALITY(ex) do { \ > + clear_thread_flag(TIF_32BIT); \ > + set_fs(TASK_SIZE_64); \ You could just use USER_DS for both of the SET_PERSONALITY macros. Will