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[23.128.96.18]) by mx.google.com with ESMTP id h3si11736269ede.590.2021.06.14.04.04.07; Mon, 14 Jun 2021 04:04:29 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=Ab6f4tq7; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235166AbhFNLE4 (ORCPT + 99 others); Mon, 14 Jun 2021 07:04:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:59166 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234037AbhFNKzk (ORCPT ); Mon, 14 Jun 2021 06:55:40 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 78D2261574; Mon, 14 Jun 2021 10:40:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623667249; bh=fZdSK81P5nrh6lyUfT53crn550lFkRCMErDvTFgLg5k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ab6f4tq7XPNjz/iJPHNhvFCf24YVmev3dw5wooSHybijGbFAKoZl36tP3F9Pi4ha2 M7x2Vlg4RjzQrsyvjJ9s/4mzJduxCmeC5mpe2ow+Cl+H5tOMSztabQ5ABN4BEwawNK BxiyY0pipWYvekNNBX1osRrSnaKa/FlKXufTbhK8= 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 5.4 83/84] ftrace: Do not blindly read the ip address in ftrace_bug() Date: Mon, 14 Jun 2021 12:28:01 +0200 Message-Id: <20210614102649.206870048@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210614102646.341387537@linuxfoundation.org> References: <20210614102646.341387537@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 @@ -1953,12 +1953,18 @@ 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;