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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 02860C433E0 for ; Mon, 22 Feb 2021 16:32:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C2E4364E76 for ; Mon, 22 Feb 2021 16:32:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230503AbhBVQcH (ORCPT ); Mon, 22 Feb 2021 11:32:07 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2594 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230008AbhBVQaH (ORCPT ); Mon, 22 Feb 2021 11:30:07 -0500 Received: from fraeml705-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4DknbT5DwLz67gS3; Tue, 23 Feb 2021 00:25:25 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml705-chm.china.huawei.com (10.206.15.54) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2106.2; Mon, 22 Feb 2021 17:29:24 +0100 Received: from localhost (10.47.74.92) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Mon, 22 Feb 2021 16:29:23 +0000 Date: Mon, 22 Feb 2021 16:28:18 +0000 From: Jonathan Cameron To: Ben Widawsky CC: Dan Williams , , , Alison Schofield , Vishal Verma , Ira Weiny , Konrad Rzeszutek Wilk Subject: Re: [PATCH v2] cxl/mem: Fix potential memory leak Message-ID: <20210222162818.00000bfb@Huawei.com> In-Reply-To: <20210221035846.680145-1-ben.widawsky@intel.com> References: <20210220215641.604535-1-ben.widawsky@intel.com> <20210221035846.680145-1-ben.widawsky@intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.74.92] X-ClientProxiedBy: lhreml713-chm.china.huawei.com (10.201.108.64) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On Sat, 20 Feb 2021 19:58:46 -0800 Ben Widawsky wrote: > When submitting a command for userspace, input and output payload bounce > buffers are allocated. For a given command, both input and output > buffers may exist and so when allocation of the input buffer fails, the > output buffer must be freed too. > > As far as I can tell, userspace can't easily exploit the leak to OOM a > machine unless the machine was already near OOM state. > > Fixes: 583fa5e71cae ("cxl/mem: Add basic IOCTL interface") > Reported-by: Konrad Rzeszutek Wilk > Signed-off-by: Ben Widawsky I'd probably have used a goto and label but I guess this works fine a well. FWIW on such a small patch. Reviewed-by: Jonathan Cameron > --- > drivers/cxl/mem.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c > index df895bcca63a..244cb7d89678 100644 > --- a/drivers/cxl/mem.c > +++ b/drivers/cxl/mem.c > @@ -514,8 +514,10 @@ static int handle_mailbox_cmd_from_user(struct cxl_mem *cxlm, > if (cmd->info.size_in) { > mbox_cmd.payload_in = vmemdup_user(u64_to_user_ptr(in_payload), > cmd->info.size_in); > - if (IS_ERR(mbox_cmd.payload_in)) > + if (IS_ERR(mbox_cmd.payload_in)) { > + kvfree(mbox_cmd.payload_out); > return PTR_ERR(mbox_cmd.payload_in); > + } > } > > rc = cxl_mem_mbox_get(cxlm);