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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 7DAF5C10DCE for ; Fri, 6 Mar 2020 15:21:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 551E9217F4 for ; Fri, 6 Mar 2020 15:21:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583508082; bh=xSBKyG4v2fBVl3hrmfT6nidsIk7FItZaTu3DdclpsZw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=gjZktTzN8TLJ7F41hYeepjCjymxTGvGnqCVs9gN75OtlNDNmK0cDBUhDxizCdL2vp 2C69Z3Gz+9Zj/Wck/rCDo/xPx7KVcp8+qkWvsuB4QKiZ89PiDGJkahTJFgVtFtU0+y /RJPPtG87oTuF/kj9KRR0U7ECTzfjPEMwoeNmZrQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727085AbgCFPVV (ORCPT ); Fri, 6 Mar 2020 10:21:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:39002 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725873AbgCFPVU (ORCPT ); Fri, 6 Mar 2020 10:21:20 -0500 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5F1292072A; Fri, 6 Mar 2020 15:21:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583508080; bh=xSBKyG4v2fBVl3hrmfT6nidsIk7FItZaTu3DdclpsZw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VoL8HU7eRNEpGt2Yv5JYMXvKHexhk9sppF+kvQSs2AW8FeDd0UfqilTwRaJd4rnhF V9qttbvc0ufjySsmBUw8Etr8ip5sQNfqn9g5zsZUabSf0LQ0ImZjIDVIdd0z7jH8IX 3H72ExwJbxaWKEg9NqqQNt6/Oih6axVIEGUvoss4= Date: Sat, 7 Mar 2020 00:21:15 +0900 From: Masami Hiramatsu To: Cheng Jian , Ingo Molnar Cc: , , , , , , , Subject: Re: [PATCH] kretprobe: check re-registration of the same kretprobe earlier Message-Id: <20200307002115.b96be2310cc553a922e1ba31@kernel.org> In-Reply-To: <1583487306-81985-1-git-send-email-cj.chengjian@huawei.com> References: <1583487306-81985-1-git-send-email-cj.chengjian@huawei.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Cheng, On Fri, 6 Mar 2020 17:35:06 +0800 Cheng Jian wrote: > Our system encountered a use-after-free when re-register a > same kretprobe. it access the hlist node in rp->free_instances > which has been released already. > > Prevent re-registration has been implemented for kprobe before, > but it's too late for kretprobe. We must check the re-registration > before re-initializing the kretprobe, otherwise it will destroy the > data and struct of the kretprobe registered, it can lead to memory > leak and use-after-free. I couldn't get how it cause use-after-free, but it causes memory leak. Anyway, if we can help to find a wrong usage, it might be good. Acked-by: Masami Hiramatsu BTW, I think we should use WARN_ON() for this error, because this means the caller is completely buggy. Thank you, > > Signed-off-by: Cheng Jian > --- > kernel/kprobes.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 2625c24..f1fc921 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1946,6 +1946,11 @@ int register_kretprobe(struct kretprobe *rp) > } > } > > + /* Return error if it's being re-registered */ > + ret = check_kprobe_rereg(&rp->kp); > + if (ret) > + return ret; > + > rp->kp.pre_handler = pre_handler_kretprobe; > rp->kp.post_handler = NULL; > rp->kp.fault_handler = NULL; > -- > 2.7.4 > -- Masami Hiramatsu