From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowmini Varadhan Subject: Re: [rds-devel] KASAN: null-ptr-deref Read in rds_ib_get_mr Date: Fri, 11 May 2018 06:46:30 -0400 Message-ID: <20180511104630.GD14952@oracle.com> References: <20180511052056.GA10547@dragonet.kaist.ac.kr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: DaeRyong Jeong , santosh.shilimkar@oracle.com, davem@davemloft.net, rds-devel@oss.oracle.com, kt0755@gmail.com, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, byoungyoung@purdue.edu To: Yanjun Zhu Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On (05/11/18 15:48), Yanjun Zhu wrote: > diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c > index e678699..2228b50 100644 > --- a/net/rds/ib_rdma.c > +++ b/net/rds/ib_rdma.c > @@ -539,11 +539,17 @@ void rds_ib_flush_mrs(void) > void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents, > struct rds_sock *rs, u32 *key_ret) > { > - struct rds_ib_device *rds_ibdev; > + struct rds_ib_device *rds_ibdev = NULL; > struct rds_ib_mr *ibmr = NULL; > - struct rds_ib_connection *ic = rs->rs_conn->c_transport_data; > + struct rds_ib_connection *ic = NULL; > int ret; > > + if (rs->rs_bound_addr == 0) { > + ret = -EPERM; > + goto out; > + } > + > + ic = rs->rs_conn->c_transport_data; > rds_ibdev = rds_ib_get_device(rs->rs_bound_addr); > if (!rds_ibdev) { > ret = -ENODEV; > > I made this raw patch. If you can reproduce this bug, please make tests > with it. I dont think this solves the problem, I think it just changes the timing under which it can still happen. what if the rds_remove_bound() in rds_bind() happens after the check for if (rs->rs_bound_addr == 0) added above by the patch I believe you need some type of synchronization (either through mutex, or some atomic flag in the rs or similar) to make sure rds_bind() and rds_ib_get_mr() are mutually exclusive. --Sowmini