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 C1264C28D13 for ; Sat, 20 Aug 2022 01:48:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235521AbiHTBs1 (ORCPT ); Fri, 19 Aug 2022 21:48:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232860AbiHTBs0 (ORCPT ); Fri, 19 Aug 2022 21:48:26 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C708C1401E; Fri, 19 Aug 2022 18:48:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5EC1861944; Sat, 20 Aug 2022 01:48:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B808CC433D7; Sat, 20 Aug 2022 01:48:19 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1oPDbF-004uUf-04; Fri, 19 Aug 2022 21:48:33 -0400 Message-ID: <20220820014832.854211663@goodmis.org> User-Agent: quilt/0.66 Date: Fri, 19 Aug 2022 21:40:36 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Masami Hiramatsu , Tzvetomir Stoyanov , Tom Zanussi , stable@vger.kernel.org Subject: [PATCH 1/4] tracing/eprobes: Do not allow eprobes to use $stack, or % for regs References: <20220820014035.531145719@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Steven Rostedt (Google)" While playing with event probes (eprobes), I tried to see what would happen if I attempted to retrieve the instruction pointer (%rip) knowing that event probes do not use pt_regs. The result was: BUG: kernel NULL pointer dereference, address: 0000000000000024 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 1847 Comm: trace-cmd Not tainted 5.19.0-rc5-test+ #309 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016 RIP: 0010:get_event_field.isra.0+0x0/0x50 Code: ff 48 c7 c7 c0 8f 74 a1 e8 3d 8b f5 ff e8 88 09 f6 ff 4c 89 e7 e8 50 6a 13 00 48 89 ef 5b 5d 41 5c 41 5d e9 42 6a 13 00 66 90 <48> 63 47 24 8b 57 2c 48 01 c6 8b 47 28 83 f8 02 74 0e 83 f8 04 74 RSP: 0018:ffff916c394bbaf0 EFLAGS: 00010086 RAX: ffff916c854041d8 RBX: ffff916c8d9fbf50 RCX: ffff916c255d2000 RDX: 0000000000000000 RSI: ffff916c255d2008 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffff916c3a2a0c08 R09: ffff916c394bbda8 R10: 0000000000000000 R11: 0000000000000000 R12: ffff916c854041d8 R13: ffff916c854041b0 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff916c9ea40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000024 CR3: 000000011b60a002 CR4: 00000000001706e0 Call Trace: get_eprobe_size+0xb4/0x640 ? __mod_node_page_state+0x72/0xc0 __eprobe_trace_func+0x59/0x1a0 ? __mod_lruvec_page_state+0xaa/0x1b0 ? page_remove_file_rmap+0x14/0x230 ? page_remove_rmap+0xda/0x170 event_triggers_call+0x52/0xe0 trace_event_buffer_commit+0x18f/0x240 trace_event_raw_event_sched_wakeup_template+0x7a/0xb0 try_to_wake_up+0x260/0x4c0 __wake_up_common+0x80/0x180 __wake_up_common_lock+0x7c/0xc0 do_notify_parent+0x1c9/0x2a0 exit_notify+0x1a9/0x220 do_exit+0x2ba/0x450 do_group_exit+0x2d/0x90 __x64_sys_exit_group+0x14/0x20 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Obviously this is not the desired result. Move the testing for TPARG_FL_TPOINT which is only used for event probes to the top of the "$" variable check, as all the other variables are not used for event probes. Also add a check in the register parsing "%" to fail if an event probe is used. Cc: stable@vger.kernel.org Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_probe.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 850a88abd33b..dec657af363c 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -283,7 +283,14 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t, int ret = 0; int len; - if (strcmp(arg, "retval") == 0) { + if (flags & TPARG_FL_TPOINT) { + if (code->data) + return -EFAULT; + code->data = kstrdup(arg, GFP_KERNEL); + if (!code->data) + return -ENOMEM; + code->op = FETCH_OP_TP_ARG; + } else if (strcmp(arg, "retval") == 0) { if (flags & TPARG_FL_RETURN) { code->op = FETCH_OP_RETVAL; } else { @@ -323,13 +330,6 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t, code->op = FETCH_OP_ARG; code->param = (unsigned int)param - 1; #endif - } else if (flags & TPARG_FL_TPOINT) { - if (code->data) - return -EFAULT; - code->data = kstrdup(arg, GFP_KERNEL); - if (!code->data) - return -ENOMEM; - code->op = FETCH_OP_TP_ARG; } else goto inval_var; @@ -384,6 +384,11 @@ parse_probe_arg(char *arg, const struct fetch_type *type, break; case '%': /* named register */ + if (flags & TPARG_FL_TPOINT) { + /* eprobes do not handle registers */ + trace_probe_log_err(offs, BAD_VAR); + break; + } ret = regs_query_register_offset(arg + 1); if (ret >= 0) { code->op = FETCH_OP_REG; -- 2.35.1