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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id c82sm8224941qkb.112.2019.07.09.12.28.55 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 09 Jul 2019 12:28:55 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hkvnK-0003m5-Te; Tue, 09 Jul 2019 16:28:54 -0300 Date: Tue, 9 Jul 2019 16:28:54 -0300 From: Jason Gunthorpe To: Dag Moxnes Cc: dledford@redhat.com, leon@kernel.org, parav@mellanox.com, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] RDMA/core: Fix race when resolving IP address Message-ID: <20190709192854.GA14462@ziepe.ca> References: <1562673026-31996-1-git-send-email-dag.moxnes@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1562673026-31996-1-git-send-email-dag.moxnes@oracle.com> 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 Tue, Jul 09, 2019 at 01:50:26PM +0200, Dag Moxnes wrote: > Use the neighbour lock when copying the MAC address from the neighbour > data struct in dst_fetch_ha. > > When not using the lock, it is possible for the function to race with > neigh_update(), causing it to copy an torn MAC address: > > rdma_resolve_addr() > rdma_resolve_ip() > addr_resolve() > addr_resolve_neigh() > fetch_ha() > dst_fetch_ha() > memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN) > > and > > net_ioctl() > arp_ioctl() > arp_rec_delete() > arp_invalidate() > neigh_update() > __neigh_update() > memcpy(&neigh->ha, lladdr, dev->addr_len) > > It is possible to provoke this error by calling rdma_resolve_addr() in a > tight loop, while deleting the corresponding ARP entry in another tight > loop. > > Fixes: 51d45974515c ("infiniband: addr: Consolidate code to fetch neighbour hardware address from dst.") > Signed-off-by: Dag Moxnes > Signed-off-by: Håkon Bugge > Reviewed-by: Parav Pandit > Signed-off-by: Jason Gunthorpe > --- > drivers/infiniband/core/addr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied to for-next, thanks Jason