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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5B64DC64E90 for ; Tue, 1 Dec 2020 23:33:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BAC6205CB for ; Tue, 1 Dec 2020 23:33:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727297AbgLAXdm (ORCPT ); Tue, 1 Dec 2020 18:33:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:50224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726891AbgLAXdj (ORCPT ); Tue, 1 Dec 2020 18:33:39 -0500 Date: Wed, 2 Dec 2020 08:32:53 +0900 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606865578; bh=RjV/+djLvuKYAFobW56Ovd1Zp//PoPVTo3mRtOOeIX0=; h=From:To:Cc:Subject:In-Reply-To:References:From; b=e0g8qDNqfCmXG96P152wtio6CtzFbaIJJ25PYUN+JAXuaq+VVoGLwLJympieK3mKN RLZZZ9q/BR0Swzs3DA9ycfnAnn3gdsW/fOGO/dK0MYDVGgiTsByRYGqSmpnx/q0hXt nKffPhXuCuUInObTP4g0EL0RPP4kNmXK6NvUReNc= From: Masami Hiramatsu To: Steven Rostedt Cc: Wang ShaoBo , , , , , , Subject: Re: [PATCH] kretprobe: avoid re-registration of the same kretprobe earlier Message-Id: <20201202083253.9dbc76704149261e131345bf@kernel.org> In-Reply-To: <20201130161850.34bcfc8a@gandalf.local.home> References: <20201124115719.11799-1-bobo.shaobowang@huawei.com> <20201130161850.34bcfc8a@gandalf.local.home> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 30 Nov 2020 16:18:50 -0500 Steven Rostedt wrote: > > Masami, > > Can you review this patch, and also, should this go to -rc and stable? > > -- Steve Thanks for ping me! > On Tue, 24 Nov 2020 19:57:19 +0800 > Wang ShaoBo wrote: > > > Our system encountered a re-init error when re-registering same kretprobe, > > where the kretprobe_instance in rp->free_instances is illegally accessed > > after re-init. Ah, OK. Anyway if re-register happens on kretprobe, it must lose instances on the list before checking re-register in register_kprobe(). So the idea looks good to me. > > Implementation to avoid re-registration has been introduced for kprobe > > before, but lags for register_kretprobe(). We must check if kprobe has > > been re-registered before re-initializing kretprobe, otherwise it will > > destroy the data struct of kretprobe registered, which can lead to memory > > leak, system crash, also some unexpected behaviors. > > > > we use check_kprobe_rereg() to check if kprobe has been re-registered > > before calling register_kretprobe(), for giving a warning message and > > terminate registration process. > > > > Signed-off-by: Wang ShaoBo > > Signed-off-by: Cheng Jian > > --- > > kernel/kprobes.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > index 41fdbb7953c6..7f54a70136f3 100644 > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -2117,6 +2117,14 @@ int register_kretprobe(struct kretprobe *rp) > > } > > } > > > > + /* > > + * Return error if it's being re-registered, > > + * also give a warning message to the developer. > > + */ > > + ret = check_kprobe_rereg(&rp->kp); > > + if (WARN_ON(ret)) > > + return ret; If you call this here, you must make sure kprobe_addr() is called on rp->kp. But if kretprobe_blacklist_size == 0, kprobe_addr() is not called before this check. So it should be in between kprobe_on_func_entry() and kretprobe_blacklist_size check, like this if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset)) return -EINVAL; addr = kprobe_addr(&rp->kp); if (IS_ERR(addr)) return PTR_ERR(addr); rp->kp.addr = addr; ret = check_kprobe_rereg(&rp->kp); if (WARN_ON(ret)) return ret; if (kretprobe_blacklist_size) { for (i = 0; > > + ret = check_kprobe_rereg(&rp->kp); Thank you, -- Masami Hiramatsu