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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id c18sm8566404qkk.73.2019.07.09.05.26.06 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 09 Jul 2019 05:26:07 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hkpCA-0001GG-Hq; Tue, 09 Jul 2019 09:26:06 -0300 Date: Tue, 9 Jul 2019 09:26:06 -0300 From: Jason Gunthorpe To: Leon Romanovsky Cc: Parav Pandit , Dag Moxnes , Doug Ledford , Parav Pandit , linux-rdma , Linux Kernel Mailing List Subject: Re: [PATCH v2] RDMA/core: Fix race when resolving IP address Message-ID: <20190709122606.GB3422@ziepe.ca> References: <1561711763-24705-1-git-send-email-dag.moxnes@oracle.com> <20190705040950.GO7212@mtr-leonro.mtl.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190705040950.GO7212@mtr-leonro.mtl.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 Fri, Jul 05, 2019 at 07:09:50AM +0300, Leon Romanovsky wrote: > On Fri, Jul 05, 2019 at 07:49:06AM +0530, Parav Pandit wrote: > > On Fri, Jun 28, 2019 at 2:20 PM Dag Moxnes wrote: > > > > > > Use neighbour lock when copying MAC address from 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 invalid MAC address. > > > > > > 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. > > > > > > Signed-off-by: Dag Moxnes > > > Signed-off-by: Håkon Bugge > > > > > > v1 -> v2: > > > * Modified implementation to improve readability > > > drivers/infiniband/core/addr.c | 9 ++++++--- > > > 1 file changed, 6 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c > > > index 2f7d141598..51323ffbc5 100644 > > > +++ b/drivers/infiniband/core/addr.c > > > @@ -333,11 +333,14 @@ static int dst_fetch_ha(const struct dst_entry *dst, > > > if (!n) > > > return -ENODATA; > > > > > > - if (!(n->nud_state & NUD_VALID)) { > > > + read_lock_bh(&n->lock); > > > + if (n->nud_state & NUD_VALID) { > > > + memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN); > > > + read_unlock_bh(&n->lock); > > > + } else { > > > + read_unlock_bh(&n->lock); > > > neigh_event_send(n, NULL); > > > ret = -ENODATA; > > > - } else { > > > - memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN); > > > } > > > > > > neigh_release(n); > > > > > Reviewed-by: Parav Pandit > > > > A sample trace such as below in commit message would be good to have. > > Or the similar one that you noticed with ARP delete sequence. > > > > neigh_changeaddr() > > neigh_flush_dev() > > n->nud_state = NUD_NOARP; > > > > Having some issues with office outlook, so replying via gmail. > > Your replies from gmail looks much better when you used Outlook - proper > spacing between quoted text and your reply. Why not use thunderbird or something? Jason