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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 886D1C433EF for ; Tue, 9 Nov 2021 08:13:14 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 3C109611BD for ; Tue, 9 Nov 2021 08:13:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3C109611BD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=6Zj4SWs2GkJABrKboImmoF1dGGCqYZb6uoJmOA12uSQ=; b=njktvkxhD7R/m3njILuBtHc3Ik eYUJ3kEPR4qfFGQ/8xEpA24EwLsS5YrEd2jCJWrfRdKvMLenOnOxd4naPJKJEFVdHDQllPMFg8zji x3z2ZWrblJD6HY5OqG7Llm7O7SvfY7e9iaEQUwKgUze3g2/TL3ZPN1mu+NZ2TplZUeRNsGzDFY7ik ZHt8qTv/50tR6w3tjijXaNKtutwU7CIDor1xNkr8lVXvQECwnHRKZp/YCZ78Qp1U6ecIfM1KYlBAt eKk6pL8Irkh6I+VaLrCjAtWh1gfBVvdZh4f+uW7vrSDm3XuTxM8yahE14ihUb4u0hJATQP0ynQl8o IGMaWeuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mkMFi-000wl7-4Z; Tue, 09 Nov 2021 08:13:10 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mkMFe-000wk4-2S for linux-nvme@lists.infradead.org; Tue, 09 Nov 2021 08:13:08 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 63D7467373; Tue, 9 Nov 2021 09:13:03 +0100 (CET) Date: Tue, 9 Nov 2021 09:13:03 +0100 From: Christoph Hellwig To: Maurizio Lombardi Cc: Sagi Grimberg , linux-nvme@lists.infradead.org, kbusch@kernel.org, axboe@fb.com, hch@lst.de Subject: Re: [PATCH] nvme-tcp: fix memory leak when freeing a queue Message-ID: <20211109081303.GC28785@lst.de> References: <20211103081817.94820-1-mlombard@redhat.com> <20211103104516.GD4840@raketa> <20211103110310.GE4840@raketa> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211103110310.GE4840@raketa> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211109_001306_284179_1D15594B X-CRM114-Status: GOOD ( 18.56 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Nov 03, 2021 at 12:03:10PM +0100, Maurizio Lombardi wrote: > > > > > > Thanks Maurizio, > > > > > > Why do we need to the pf_cache.va protection? nvme_tcp_free_queue > > > is already protected against re-entry with the NVME_TCP_Q_ALLOCATED > > > bit. > > > > > > > It's not the re-entry what worried me, I thought that nvme_tcp_free_queue() > > might be called before page_frag_alloc() had the chance to initialize the pf_cache, triggering > > a NULL pointer dereference. I am doing some tests right now and it seems not to be > > possible so maybe we can drop the "if". > > Oh wait, if nvme_tcp_setup_ctrl() fails it could call nvme_tcp_destroy_io_queues() and > iI guess that in that case the pf_cache is not initialized, so the if(pf_cache.va) protection > is necessary. Sagi, does this look good to you now?