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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 96282C433B4 for ; Mon, 26 Apr 2021 05:09:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6BFBD61157 for ; Mon, 26 Apr 2021 05:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231733AbhDZFJl (ORCPT ); Mon, 26 Apr 2021 01:09:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:48182 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230162AbhDZFJi (ORCPT ); Mon, 26 Apr 2021 01:09:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C2AB861153; Mon, 26 Apr 2021 05:08:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619413734; bh=FB9IZe4W6KBfmEifqMgY62/Fy4ZapV8Jm17uzmJTlRo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LRLCkuPqBrdjUbLotyual5dcOE4bTL5Qnwjc0FjcoT8m1CtPfarbLtkC93348GL8y 7dhrAZJxV12G0/BSiAGjS3LmcJdg3y5kinISGWqYwf/bqnS2EMs4DopAvmscpdpvgC J1X6s96BGpCu5eyek2BDAnufrZo0VgMW6zKwBhBqxkCB73DtY+iAPVWtHlSiJQngPi mfBH2EjO8hvz7xMRajg2tqblD6gi30SHnzxeVxMmGu3GFrOFFYwA3yuzTWusA6H+tp tFqRm6lr7zH/wghmBMs99tzxcZnrxibGKMMb6CDUy1xCnEYSsPW0pDGew7ZzjXY0Ut 10j8TeIHtkx+g== Date: Mon, 26 Apr 2021 08:08:50 +0300 From: Leon Romanovsky To: Lv Yunlong Cc: bmt@zurich.ibm.com, dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr Message-ID: References: <20210426011647.3561-1-lyl2019@mail.ustc.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210426011647.3561-1-lyl2019@mail.ustc.edu.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 25, 2021 at 06:16:47PM -0700, Lv Yunlong wrote: > Our code analyzer reported a uaf. Can you please share more details about this "code analyzer"? Thanks > > In siw_alloc_mr, it calls siw_mr_add_mem(mr,..). In the implementation > of siw_mr_add_mem(), mem is assigned to mr->mem and then mem is freed > via kfree(mem) if xa_alloc_cyclic() failed. Here, mr->mem still point > to a freed object. After, the execution continue up to the err_out branch > of siw_alloc_mr, and the freed mr->mem is used in siw_mr_drop_mem(mr). > > My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {} > section, to avoid the uaf. > > Fixes: 2251334dcac9e ("rdma/siw: application buffer management") > Signed-off-by: Lv Yunlong > --- > drivers/infiniband/sw/siw/siw_mem.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c > index 34a910cf0edb..96b38cfbb513 100644 > --- a/drivers/infiniband/sw/siw/siw_mem.c > +++ b/drivers/infiniband/sw/siw/siw_mem.c > @@ -106,8 +106,6 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj, > mem->perms = rights & IWARP_ACCESS_MASK; > kref_init(&mem->ref); > > - mr->mem = mem; > - > get_random_bytes(&next, 4); > next &= 0x00ffffff; > > @@ -116,6 +114,8 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj, > kfree(mem); > return -ENOMEM; > } > + > + mr->mem = mem; > /* Set the STag index part */ > mem->stag = id << 8; > mr->base_mr.lkey = mr->base_mr.rkey = mem->stag; > -- > 2.25.1 > >