From patchwork Mon Jun 14 10:27:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 460447 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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, 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 972F6C2B9F4 for ; Mon, 14 Jun 2021 10:33:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70486613F0 for ; Mon, 14 Jun 2021 10:33:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233059AbhFNKf2 (ORCPT ); Mon, 14 Jun 2021 06:35:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:38772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233338AbhFNKds (ORCPT ); Mon, 14 Jun 2021 06:33:48 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4233F60D07; Mon, 14 Jun 2021 10:31:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623666701; bh=K2QGJxLnGYUHtMfavV/sEVxakvSo/ZfT7/pyzJ5yUis=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eUi6JFG+0N5Zv3fozTauwwRLdWUn28V4qopC432X/W6VWpK2uICWeKL0BQGvSh5gA 3YCRvHssmoqmg1lwErKY5Wt5dhOF8tRXo5JldoLRrrevToULiVa5SbQtf4qs/nCaGy 2p/ZmisnwSStLZkcMfEue0O+LmrjHW14luc9gDFI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark-PK Tsai , "Steven Rostedt (VMware)" Subject: [PATCH 4.9 41/42] ftrace: Do not blindly read the ip address in ftrace_bug() Date: Mon, 14 Jun 2021 12:27:32 +0200 Message-Id: <20210614102644.016353739@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210614102642.700712386@linuxfoundation.org> References: <20210614102642.700712386@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Steven Rostedt (VMware) commit 6c14133d2d3f768e0a35128faac8aa6ed4815051 upstream. It was reported that a bug on arm64 caused a bad ip address to be used for updating into a nop in ftrace_init(), but the error path (rightfully) returned -EINVAL and not -EFAULT, as the bug caused more than one error to occur. But because -EINVAL was returned, the ftrace_bug() tried to report what was at the location of the ip address, and read it directly. This caused the machine to panic, as the ip was not pointing to a valid memory address. Instead, read the ip address with copy_from_kernel_nofault() to safely access the memory, and if it faults, report that the address faulted, otherwise report what was in that location. Link: https://lore.kernel.org/lkml/20210607032329.28671-1-mark-pk.tsai@mediatek.com/ Cc: stable@vger.kernel.org Fixes: 05736a427f7e1 ("ftrace: warn on failure to disable mcount callers") Reported-by: Mark-PK Tsai Tested-by: Mark-PK Tsai Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ftrace.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1961,12 +1961,18 @@ static int ftrace_hash_ipmodify_update(s static void print_ip_ins(const char *fmt, const unsigned char *p) { + char ins[MCOUNT_INSN_SIZE]; int i; + if (probe_kernel_read(ins, p, MCOUNT_INSN_SIZE)) { + printk(KERN_CONT "%s[FAULT] %px\n", fmt, p); + return; + } + printk(KERN_CONT "%s", fmt); for (i = 0; i < MCOUNT_INSN_SIZE; i++) - printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]); + printk(KERN_CONT "%s%02x", i ? ":" : "", ins[i]); } enum ftrace_bug_type ftrace_bug_type;