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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 DE1DCC433B4 for ; Tue, 18 May 2021 18:44:19 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AB48E61261 for ; Tue, 18 May 2021 18:44:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB48E61261 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Fl4fT0pwdz3bsp for ; Wed, 19 May 2021 04:44:17 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.235.10; helo=pegase2.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Fl4f60PNKz2yX4 for ; Wed, 19 May 2021 04:43:53 +1000 (AEST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4Fl4dw4vn7z9sX3; Tue, 18 May 2021 20:43:48 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6PoU40IGTisj; Tue, 18 May 2021 20:43:48 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4Fl4dw3PzFz9sX2; Tue, 18 May 2021 20:43:48 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E9C468B7D7; Tue, 18 May 2021 20:43:47 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id KH3a5tPj9yhx; Tue, 18 May 2021 20:43:47 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 5EEC28B7C2; Tue, 18 May 2021 20:43:47 +0200 (CEST) Subject: Re: [PATCH v8 27/30] powerpc/kprobes: Don't allow breakpoints on suffixes To: Jordan Niethe , linuxppc-dev@lists.ozlabs.org References: <20200506034050.24806-1-jniethe5@gmail.com> <20200506034050.24806-28-jniethe5@gmail.com> From: Christophe Leroy Message-ID: Date: Tue, 18 May 2021 20:43:39 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20200506034050.24806-28-jniethe5@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alistair@popple.id.au, npiggin@gmail.com, bala24@linux.ibm.com, naveen.n.rao@linux.vnet.ibm.com, dja@axtens.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 06/05/2020 à 05:40, Jordan Niethe a écrit : > Do not allow inserting breakpoints on the suffix of a prefix instruction > in kprobes. > > Signed-off-by: Jordan Niethe > --- > v8: Add this back from v3 > --- > arch/powerpc/kernel/kprobes.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c > index 33d54b091c70..227510df8c55 100644 > --- a/arch/powerpc/kernel/kprobes.c > +++ b/arch/powerpc/kernel/kprobes.c > @@ -106,7 +106,9 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) > int arch_prepare_kprobe(struct kprobe *p) > { > int ret = 0; > + struct kprobe *prev; > struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr); > + struct ppc_inst prefix = ppc_inst_read((struct ppc_inst *)(p->addr - 1)); What if p->addr is the first word of a page and the previous page is not mapped ? > > if ((unsigned long)p->addr & 0x03) { > printk("Attempt to register kprobe at an unaligned address\n"); > @@ -114,6 +116,17 @@ int arch_prepare_kprobe(struct kprobe *p) > } else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) { > printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n"); > ret = -EINVAL; > + } else if (ppc_inst_prefixed(prefix)) { If p->addr - 2 contains a valid prefixed instruction, then p->addr - 1 contains the suffix of that prefixed instruction. Are we sure a suffix can never ever be misinterpreted as the prefix of a prefixed instruction ? > + printk("Cannot register a kprobe on the second word of prefixed instruction\n"); > + ret = -EINVAL; > + } > + preempt_disable(); > + prev = get_kprobe(p->addr - 1); > + preempt_enable_no_resched(); > + if (prev && > + ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)prev->ainsn.insn))) { > + printk("Cannot register a kprobe on the second word of prefixed instruction\n"); > + ret = -EINVAL; > } > > /* insn must be on a special executable page on ppc64. This is >