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=-11.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 AD297C07E9C for ; Thu, 8 Jul 2021 04:14:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82BAB61CD3 for ; Thu, 8 Jul 2021 04:14:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229571AbhGHEQz (ORCPT ); Thu, 8 Jul 2021 00:16:55 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:10327 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbhGHEQy (ORCPT ); Thu, 8 Jul 2021 00:16:54 -0400 Received: from dggeme765-chm.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4GL2qw2fq9z76HT; Thu, 8 Jul 2021 12:09:48 +0800 (CST) Received: from DESKTOP-E0KHRBE.china.huawei.com (10.67.103.82) by dggeme765-chm.china.huawei.com (10.3.19.111) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Thu, 8 Jul 2021 12:14:10 +0800 From: Shaobo Huang To: , , , , , , , , CC: , , , , , , , , Subject: Re: [PATCH] ARM: fix panic when kasan and kprobe are enabled Date: Thu, 8 Jul 2021 12:14:09 +0800 Message-ID: <20210708041409.34168-1-huangshaobo6@huawei.com> X-Mailer: git-send-email 2.21.0.windows.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.67.103.82] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggeme765-chm.china.huawei.com (10.3.19.111) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 11 Feb 2021 at 09:40, Ard Biesheuvel wrote: > > > From: huangshaobo > > > > arm32 uses software to simulate the instruction replaced > > by kprobe. some instructions may be simulated by constructing > > assembly functions. therefore, before executing instruction > > simulation, it is necessary to construct assembly function > > execution environment in C language through binding registers. > > after kasan is enabled, the register binding relationship will > > be destroyed, resulting in instruction simulation errors and > > causing kernel panic. > > > > the kprobe emulate instruction function is distributed in three > > files: actions-common.c actions-arm.c actions-thumb.c, so disable > > KASAN when compiling these files. > > > > for example, use kprobe insert on cap_capable+20 after kasan > > enabled, the cap_capable assembly code is as follows: > > : > > e92d47f0 push {r4, r5, r6, r7, r8, r9, sl, lr} > > e1a05000 mov r5, r0 > > e280006c add r0, r0, #108 ; 0x6c > > e1a04001 mov r4, r1 > > e1a06002 mov r6, r2 > > e59fa090 ldr sl, [pc, #144] ; > > ebfc7bf8 bl c03aa4b4 <__asan_load4> > > e595706c ldr r7, [r5, #108] ; 0x6c > > e2859014 add r9, r5, #20 > > ...... > > The emulate_ldr assembly code after enabling kasan is as follows: > > c06f1384 : > > e92d47f0 push {r4, r5, r6, r7, r8, r9, sl, lr} > > e282803c add r8, r2, #60 ; 0x3c > > e1a05000 mov r5, r0 > > e7e37855 ubfx r7, r5, #16, #4 > > e1a00008 mov r0, r8 > > e1a09001 mov r9, r1 > > e1a04002 mov r4, r2 > > ebf35462 bl c03c6530 <__asan_load4> > > e357000f cmp r7, #15 > > e7e36655 ubfx r6, r5, #12, #4 > > e205a00f and sl, r5, #15 > > 0a000001 beq c06f13bc > > e0840107 add r0, r4, r7, lsl #2 > > ebf3545c bl c03c6530 <__asan_load4> > > e084010a add r0, r4, sl, lsl #2 > > ebf3545a bl c03c6530 <__asan_load4> > > e2890010 add r0, r9, #16 > > ebf35458 bl c03c6530 <__asan_load4> > > e5990010 ldr r0, [r9, #16] > > e12fff30 blx r0 > > e356000f cm r6, #15 > > 1a000014 bne c06f1430 > > e1a06000 mov r6, r0 > > e2840040 add r0, r4, #64 ; 0x40 > > ...... > > when running in emulate_ldr to simulate the ldr instruction, panic > > occurred, and the log is as follows: > > Unable to handle kernel NULL pointer dereference at virtual address > > 00000090 > > pgd = ecb46400 > > [00000090] *pgd=2e0fa003, *pmd=00000000 > > Internal error: Oops: 206 [#1] SMP ARM > > PC is at cap_capable+0x14/0xb0 > > LR is at emulate_ldr+0x50/0xc0 > > psr: 600d0293 sp : ecd63af8 ip : 00000004 fp : c0a7c30c > > r10: 00000000 r9 : c30897f4 r8 : ecd63cd4 > > r7 : 0000000f r6 : 0000000a r5 : e59fa090 r4 : ecd63c98 > > r3 : c06ae294 r2 : 00000000 r1 : b7611300 r0 : bf4ec008 > > Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment user > > Control: 32c5387d Table: 2d546400 DAC: 55555555 > > Process bash (pid: 1643, stack limit = 0xecd60190) > > (cap_capable) from (kprobe_handler+0x218/0x340) > > (kprobe_handler) from (kprobe_trap_handler+0x24/0x48) > > (kprobe_trap_handler) from (do_undefinstr+0x13c/0x364) > > (do_undefinstr) from (__und_svc_finish+0x0/0x30) > > (__und_svc_finish) from (cap_capable+0x18/0xb0) > > (cap_capable) from (cap_vm_enough_memory+0x38/0x48) > > (cap_vm_enough_memory) from > > (security_vm_enough_memory_mm+0x48/0x6c) > > (security_vm_enough_memory_mm) from > > (copy_process.constprop.5+0x16b4/0x25c8) > > (copy_process.constprop.5) from (_do_fork+0xe8/0x55c) > > (_do_fork) from (SyS_clone+0x1c/0x24) > > (SyS_clone) from (__sys_trace_return+0x0/0x10) > > Code: 0050a0e1 6c0080e2 0140a0e1 0260a0e1 (f801f0e7) > > > > Fixes: 35aa1df43283 ("ARM kprobes: instruction single-stepping support") > > Fixes: 421015713b30 ("ARM: 9017/2: Enable KASan for ARM") > > Signed-off-by: huangshaobo > Acked-by: Ard Biesheuvel Maintainer ping? thanks, ShaoBo Huang