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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 79EA7C2D0DB for ; Tue, 28 Jan 2020 18:25:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5235920716 for ; Tue, 28 Jan 2020 18:25:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="E1HO014q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726496AbgA1SZZ (ORCPT ); Tue, 28 Jan 2020 13:25:25 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:41834 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726569AbgA1SZZ (ORCPT ); Tue, 28 Jan 2020 13:25:25 -0500 Received: by mail-qt1-f194.google.com with SMTP id l19so5486335qtq.8 for ; Tue, 28 Jan 2020 10:25:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=cgxKMpHFKn4hSZK4Ab5jy2YFw30mUYxzmDc6cWww/r8=; b=E1HO014qRTE0dWscy4rsG+l6a3D3DA79u1EKlIQBVmlLE8aFXoW5lu3q0/h92pv/3C o16lxazQ4rqQWzY1Zhku+naupwDtLyU2eTfctYeHzCfJOuzOlqtYmKYg0ssjcddIUax6 1bvvftL7XCgCP9SuLQDXi7aZfIeBGpubH8dYQpP/pR1gHzJe6H9jnBuDudkfxZMwLBdq pahFW1toJ1/Rdj8jdtW/DZAKQ4dpP9BtTkxWGLlPYwg5kQUp5bvwDZEnn6c2cI8N1tb7 5OeSMJMsQAq2TCQlelVynkN11OTaLPC1mnHds3dxpi5d8dgsiMZGwmLaEaNJFhhE9iTU s6CQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=cgxKMpHFKn4hSZK4Ab5jy2YFw30mUYxzmDc6cWww/r8=; b=TVeGZil1OBUw3QImXbT0s+OBX359k1OcBzkL9Av+70Ru5cxNE3pqP4+LjN4nyoRVCT 72onpPcqYdiRVHsA+BFJCUWYhiaFi7BhbdbQ/D76rQJQrUPFZHRsWoPDKMlE31eGUUpT MAXYehHn4SqE8AHDeghWdVP7RaBAe9Le7aMe15YYgTBqLL+URnKy6xRQbEDQo8n7lY1G Q+LvrS4qEGbN2ZdYy2AcutNXC5BAXnIYSMeWoHVJajsLIYfhnmYHqs9UgL//FOtkX+o6 s04p/gVunjaG2DUgNDUCb9Yf51+bfJzGtaesZY8VSvQbrj6h/24RE4kZz036ykVnRjgb vz9w== X-Gm-Message-State: APjAAAVzuRKGLzyzAA5BMJ3fD5U0HTW2hv87ZZ6LETqMqgLR95LAFO5U 0IDYj6wiGbFAhj9yMTyBLgaMvw== X-Google-Smtp-Source: APXvYqw4pT9Yr5WmPQj65uZQs2IMfacwZfucAbF9pJG9pVAyVj1krrYlW/EhH60VpuqH/JaYX3KP2w== X-Received: by 2002:ac8:3f88:: with SMTP id d8mr6905701qtk.382.1580235924571; Tue, 28 Jan 2020 10:25:24 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-68-57-212.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.57.212]) by smtp.gmail.com with ESMTPSA id g6sm3830195qtp.53.2020.01.28.10.25.23 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 28 Jan 2020 10:25:24 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iwVYB-0008SI-HM; Tue, 28 Jan 2020 14:25:23 -0400 Date: Tue, 28 Jan 2020 14:25:23 -0400 From: Jason Gunthorpe To: Leon Romanovsky Cc: Doug Ledford , Leon Romanovsky , RDMA mailing list , Parav Pandit Subject: Re: [PATCH rdma-next 1/7] RDMA/cma: Fix unbalanced cm_id reference count during address resolve Message-ID: <20200128182523.GA32407@ziepe.ca> References: <20200126142652.104803-1-leon@kernel.org> <20200126142652.104803-2-leon@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200126142652.104803-2-leon@kernel.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Sun, Jan 26, 2020 at 04:26:46PM +0200, Leon Romanovsky wrote: > From: Parav Pandit > > Below cited commit missed to consider AF_IB and loopback code flow in > rdma_resolve_addr(). > This leads to unbalanced cm_id refcount in cma_work_handler() which > puts the refcount which was not incremented in rdma_resolve_addr(). > > A call trace is observed with such code flow. > > BUG: unable to handle kernel NULL pointer dereference at (null) > [] __mutex_lock_slowpath+0x166/0x1d0 > [] mutex_lock+0x1f/0x2f > [] cma_work_handler+0x25/0xa0 > [] process_one_work+0x17f/0x440 > [] worker_thread+0x126/0x3c0 > > Hence, hold the cm_id reference when scheduling resolve work item. > > Fixes: 722c7b2bfead ("RDMA/{cma, core}: Avoid callback on rdma_addr_cancel()") > Signed-off-by: Parav Pandit > Signed-off-by: Leon Romanovsky > --- > drivers/infiniband/core/cma.c | 2 ++ > 1 file changed, 2 insertions(+) It is very hard to read this flow around the 'work', the incr of the refcount in rdma_resolve_route() seems very poorly placed. But this looks correct, so applied to for-next Thanks, Jason