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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A52B6C433EF for ; Fri, 19 Nov 2021 03:04:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78E7D61458 for ; Fri, 19 Nov 2021 03:04:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230131AbhKSDHu (ORCPT ); Thu, 18 Nov 2021 22:07:50 -0500 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:36887 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229909AbhKSDHu (ORCPT ); Thu, 18 Nov 2021 22:07:50 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R251e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=rongwei.wang@linux.alibaba.com;NM=1;PH=DS;RN=12;SR=0;TI=SMTPD_---0UxG4U3T_1637291086; Received: from 30.240.104.212(mailfrom:rongwei.wang@linux.alibaba.com fp:SMTPD_---0UxG4U3T_1637291086) by smtp.aliyun-inc.com(127.0.0.1); Fri, 19 Nov 2021 11:04:47 +0800 Message-ID: Date: Fri, 19 Nov 2021 11:04:45 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:95.0) Gecko/20100101 Thunderbird/95.0 Subject: Re: [PATCH v2 1/2] arm64: trans_pgd: fix incorrect use of pmd_populate_kernel in copy_pte() Content-Language: en-US From: Rongwei Wang To: catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, james.morse@arm.com, ardb@kernel.org, tabba@google.com, akpm@linux-foundation.org, rppt@kernel.org, anshuman.khandual@arm.com, kernelfans@gmail.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20211030183200.51295-1-rongwei.wang@linux.alibaba.com> <20211114201650.5542-1-rongwei.wang@linux.alibaba.com> <20211114201650.5542-2-rongwei.wang@linux.alibaba.com> In-Reply-To: <20211114201650.5542-2-rongwei.wang@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ard and Pingfan This bug I had fix and send out Patch v1 in 31 Oct. And it seems my patch had been ignored, and Pingfan's patch had been reviewed: This is link of Pingfan's patch: https://lore.kernel.org/linux-arm-kernel/20211111060316.12438-1-kernelfans@gmail.com/#r It seems that I am not subscribe linux-arm-kernel successfully. Thanks! On 11/15/21 4:16 AM, Rongwei Wang wrote: > In commit 5de59884ac0e ("arm64: trans_pgd: pass NULL instead > of init_mm to *_populate functions"), simply replace init_mm > with NULL for pmd_populate_kernel. But in commit 59511cfd08f3 > ("arm64: mm: use XN table mapping attributes for user/kernel > mappings"), adding the check of mm context in > pmd_populate_kernel. And these changes will cause a crash when > executing copy_pte/trans_pgd.c, as follows: > > kernel BUG at arch/arm64/include/asm/pgalloc.h:79! > Internal error: Oops - BUG: 0 [#1] SMP > Modules linked in: rfkill(E) aes_ce_blk(E) aes_ce_cipher(E) ... > CPU: 21 PID: 1617 Comm: a.out Kdump: loaded Tainted: ... 5.15.0-rc7-mm1+ #8 > Hardware name: ECS, BIOS 0.0.0 02/06/2015 > pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : trans_pgd_create_copy+0x4ac/0x4f0 > lr : trans_pgd_create_copy+0x34c/0x4f0 > sp : ffff80001bf2bc50 > x29: ffff80001bf2bc50 x28: ffff0010067f1000 x27: ffff800011072000 > x26: ffff001fffff8000 x25: ffff008000000000 x24: 0040000000000041 > x23: 0040000000000001 x22: ffff80001bf2bd68 x21: ffff80001188ded8 > x20: ffff800000000000 x19: ffff000000000000 x18: 0000000000000000 > x17: 0000000000000000 x16: 0000000000000000 x15: 00000000200004c0 > x14: ffff00003fffffff x13: ffff007fffffffff x12: ffff800010f882a8 > x11: 0000000000face57 x10: 0000000000000001 x9 : 0000000000000000 > x8 : ffff00100cece000 x7 : ffff001001c9f000 x6 : ffff00100ae40000 > x5 : 0000000000000040 x4 : 0000000000000000 x3 : ffff001fffff7000 > x2 : ffff000000200000 x1 : ffff000040000000 x0 : ffff00100cecd000 > Call trace: > trans_pgd_create_copy+0x4ac/0x4f0 > machine_kexec_post_load+0x94/0x3bc > do_kexec_load+0x11c/0x2e0 > __arm64_sys_kexec_load+0xa8/0xf4 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x58/0x190 > do_el0_svc+0x2c/0x90 > el0_svc+0x28/0xe0 > el0t_64_sync_handler+0xb0/0xb4 > el0t_64_sync+0x180/0x184 > Code: f90000c0 d5033a9f d5033fdf 17ffff7b (d4210000) > ---[ end trace cc5461ffe1a085db ]--- > Kernel panic - not syncing: Oops - BUG: Fatal exception > > This bug can be reproduced by a user case: > > void execute_kexec_load(void) > { > syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); > syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul); > syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); > > *(uint64_t*)0x200004c0 = 0; > *(uint64_t*)0x200004c8 = 0; > *(uint64_t*)0x200004d0 = 0; > *(uint64_t*)0x200004d8 = 0; > syscall(__NR_kexec_load, 0ul, 1ul, 0x200004c0ul, 0ul); > } > > And this patch make a simple change, just restoring init_mm > for 'pmd_populate_kernel' in 'copy_pte'. > > Fixes: 59511cfd08f3 ("arm64: mm: use XN table mapping attributes for user/kernel mappings") > Reported-by: Abaci > Signed-off-by: Rongwei Wang > --- > arch/arm64/mm/trans_pgd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c > index d7da8ca40d2e..5275ca312360 100644 > --- a/arch/arm64/mm/trans_pgd.c > +++ b/arch/arm64/mm/trans_pgd.c > @@ -67,7 +67,7 @@ static int copy_pte(struct trans_pgd_info *info, pmd_t *dst_pmdp, > dst_ptep = trans_alloc(info); > if (!dst_ptep) > return -ENOMEM; > - pmd_populate_kernel(NULL, dst_pmdp, dst_ptep); > + pmd_populate_kernel(&init_mm, dst_pmdp, dst_ptep); > dst_ptep = pte_offset_kernel(dst_pmdp, start); > > src_ptep = pte_offset_kernel(src_pmdp, start); >