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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,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 2D4D0C47082 for ; Mon, 7 Jun 2021 18:14:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C16361003 for ; Mon, 7 Jun 2021 18:14:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231181AbhFGSQA (ORCPT ); Mon, 7 Jun 2021 14:16:00 -0400 Received: from mailgw01.mediatek.com ([210.61.82.183]:58367 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S230212AbhFGSP6 (ORCPT ); Mon, 7 Jun 2021 14:15:58 -0400 X-UUID: b43cadc9048245d9aaacea593f25c901-20210608 X-UUID: b43cadc9048245d9aaacea593f25c901-20210608 Received: from mtkmbs10n1.mediatek.inc [(172.21.101.34)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1890285528; Tue, 08 Jun 2021 02:14:05 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs05n1.mediatek.inc (172.21.101.15) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 8 Jun 2021 02:14:03 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Tue, 8 Jun 2021 02:14:03 +0800 From: Mark-PK Tsai To: CC: , , , , , , , , Subject: Re: [PATCH] arm64: ftrace: don't dereference a probably invalid address Date: Tue, 8 Jun 2021 02:14:03 +0800 Message-ID: <20210607181403.4017-1-mark-pk.tsai@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20210607105217.772214e5@oasis.local.home> References: <20210607105217.772214e5@oasis.local.home> MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Mon, 7 Jun 2021 22:15:22 +0800 > Mark-PK Tsai wrote: > > > And the crash is becuase kernel trying to read *rec->ip in print_ip_ins() if > > ftrace_bug() get error code -EINVAL. > > Right, so the actual fix should be something like this: > > [ not tested, nor even compiled ] > > -- Steve > I just test this patch, and turns out it work well. All my modification is only rename copy_from_kernel_nofault into probe_kernel_read because the older kernel version I use. Then the kernel will show the error mesage instead of panic as following. [ 0.000000] ftrace failed to modify [ 0.000000] [<0000000000000020>] 0x20 [ 0.000000] actual: [FAULT](0000000000000020) Should I resend this patch as v2? Or you will upstream this fix? > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 2e8a3fde7104..72ef4dccbcc4 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1967,12 +1967,18 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, > > static void print_ip_ins(const char *fmt, const unsigned char *p) > { > + char ins[MCOUNT_INSN_SIZE]; > int i; > > + if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) { > + printk(KERN_CONT "%s[FAULT](%px)", 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;