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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 61323C00144 for ; Mon, 1 Aug 2022 03:45:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238241AbiHADo6 (ORCPT ); Sun, 31 Jul 2022 23:44:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230343AbiHADou (ORCPT ); Sun, 31 Jul 2022 23:44:50 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90AFC25FF; Sun, 31 Jul 2022 20:44:48 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Lx3mw00JHzWfth; Mon, 1 Aug 2022 11:40:47 +0800 (CST) Received: from dggpemm500013.china.huawei.com (7.185.36.172) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 1 Aug 2022 11:44:46 +0800 Received: from [127.0.0.1] (10.67.108.67) by dggpemm500013.china.huawei.com (7.185.36.172) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 1 Aug 2022 11:44:45 +0800 Message-ID: Date: Mon, 1 Aug 2022 11:44:45 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.0 Subject: Re: [PATCH] kprobes: Forbid probing on kprobe_insn_slot Content-Language: en-US To: "Masami Hiramatsu (Google)" CC: , , , , , References: <20220727032058.60444-1-chenzhongjin@huawei.com> <20220801004854.9c2b36f38fe5ad19b2271196@kernel.org> From: Chen Zhongjin In-Reply-To: <20220801004854.9c2b36f38fe5ad19b2271196@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.108.67] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500013.china.huawei.com (7.185.36.172) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2022/7/31 23:48, Masami Hiramatsu (Google) wrote: > On Wed, 27 Jul 2022 11:20:58 +0800 > Chen Zhongjin wrote: > >> Syzkaller reported a BUG on arm64: >> Unrecoverable kprobe detected. >> Dumping kprobe: >> Name: (null) >> Offset: 0 >> Address: 0xffffa00010019000 >> ------------[ cut here ]------------ >> kernel BUG at arch/arm64/kernel/probes/kprobes.c:235! >> Internal error: Oops - BUG: 0 [#1] SMP >> Modules linked in: >> CPU: 1 PID: 31060 Comm: syz-executor.6 Not tainted 5.10.0 #11 >> ... >> Call trace: >>  reenter_kprobe arch/arm64/kernel/probes/kprobes.c:234 [inline] >>  kprobe_handler+0x23c/0x26c arch/arm64/kernel/probes/kprobes.c:339 >>  kprobe_breakpoint_handler+0x24/0x34 arch/arm64/kernel/probes/kprobes.c:406 >>  call_break_hook+0xf4/0x13c arch/arm64/kernel/debug-monitors.c:322 >>  brk_handler+0x2c/0xa0 arch/arm64/kernel/debug-monitors.c:329 >>  do_debug_exception+0x140/0x230 arch/arm64/mm/fault.c:867 >>  el1_dbg+0x38/0x50 arch/arm64/kernel/entry-common.c:182 >>  el1_sync_handler+0xf4/0x150 arch/arm64/kernel/entry-common.c:219 >>  el1_sync+0x74/0x100 arch/arm64/kernel/entry.S:665 >>  0xffffa00010019000 >>  do_futex+0x2f4/0x370 kernel/futex.c:3735 >>  __do_sys_futex kernel/futex.c:3798 [inline] >>  __se_sys_futex kernel/futex.c:3764 [inline] >>  __arm64_sys_futex+0x168/0x3a0 kernel/futex.c:3764 >>  __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] >>  invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] >>  el0_svc_common.constprop.0+0xf4/0x414 arch/arm64/kernel/syscall.c:155 >>  do_el0_svc+0x50/0x11c arch/arm64/kernel/syscall.c:217 >>  el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353 >>  el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369 >>  el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683 >> Code: 91018360 97ff1838 aa1703e0 97ff1fdf (d4210000) >> ---[ end trace 767503e946e01b15 ]--- >> >> Syzbot tried to porbe on a kprobe_insn_slot. >> >> kprobe will replace instruciton with a break and store the origin one >> on kprobe_insn_slot. However these slots are not in .kprobes.text and >> exported by perf_event_ksymbol so can be probed by perf interface. >> >> Probing these slots will triggers kprobe handler inside single step >> process and for some architectures such as arm64 this will causes a >> bug(). >> >> These slots are kprobe process so they should not be probed anyway. >> Add kprobe_insn_slot check when register_kprobe to forbid probing on >> these slots. > Oops, good catch! > > Previously this was not counted as text area, but now the kernel_text_address() > returns true for these trampoline buffers. > > In this case, I think kprobes should be limited to probe only > core_kernel_text and module_text. > Can you use is_module_text_address() and core_kernel_text() instead? > Below can allow kprobes probing on other trampolines like ftrace and > bpf. > Also, you may need this tag; > > Fixes: 5b485629ba0d ("kprobes, extable: Identify kprobes trampolines as kernel text area") > > Thank you, Thanks for review! Please see next version here: https://lkml.org/lkml/2022/7/31/436 [PATCH v3] kprobes: Forbid probing on trampoline and bpf prog >> Signed-off-by: Chen Zhongjin >> --- >> kernel/kprobes.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/kernel/kprobes.c b/kernel/kprobes.c >> index f214f8c088ed..3e798b62db70 100644 >> --- a/kernel/kprobes.c >> +++ b/kernel/kprobes.c >> @@ -1562,6 +1562,8 @@ static int check_kprobe_address_safe(struct kprobe *p, >> /* Ensure it is not in reserved area nor out of text */ >> if (!kernel_text_address((unsigned long) p->addr) || >> within_kprobe_blacklist((unsigned long) p->addr) || >> + is_kprobe_insn_slot((unsigned long) p->addr) || >> + is_kprobe_optinsn_slot((unsigned long) p->addr) || >> jump_label_text_reserved(p->addr, p->addr) || >> static_call_text_reserved(p->addr, p->addr) || >> find_bug((unsigned long)p->addr)) { >> -- >> 2.17.1 >> Best, Chen