[PATCH 3.16 223/328] RDMA/cma: Protect cma dev list with lock

Ben Hutchings
2018-12-09T21:59:29Z

From: Parav Pandit <parav@mellanox.com>

commit 954a8e3aea87e896e320cf648c1a5bbe47de443e upstream.

When AF_IB addresses are used during rdma_resolve_addr() a lock is not
held. A cma device can get removed while list traversal is in progress
which may lead to crash. ie

CPU0 CPU1
==== ====
rdma_resolve_addr()
cma_resolve_ib_dev()
list_for_each() cma_remove_one()
cur_dev->device mutex_lock(&lock)
list_del();
mutex_unlock(&lock);
cma_process_remove();

Therefore, hold a lock while traversing the list which avoids such
situation.

Fixes: f17df3b0dede ("RDMA/cma: Add support for AF_IB to rdma_resolve_addr()")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/infiniband/core/cma.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -434,6 +434,7 @@ static int cma_resolve_ib_dev(struct rdm
dgid = (union ib_gid *) &addr->sib_addr;
pkey = ntohs(addr->sib_pkey);

+ mutex_lock(&lock);
list_for_each_entry(cur_dev, &dev_list, list) {
if (rdma_node_get_transport(cur_dev->device->node_type) != RDMA_TRANSPORT_IB)
continue;
@@ -455,18 +456,19 @@ static int cma_resolve_ib_dev(struct rdm
cma_dev = cur_dev;
sgid = gid;
id_priv->id.port_num = p;
+ goto found;
}
}
}
}
-
- if (!cma_dev)
- return -ENODEV;
+ mutex_unlock(&lock);
+ return -ENODEV;

found:
cma_attach_to_dev(id_priv, cma_dev);
- addr = (struct sockaddr_ib *) cma_src_addr(id_priv);
- memcpy(&addr->sib_addr, &sgid, sizeof sgid);
+ mutex_unlock(&lock);
+ addr = (struct sockaddr_ib *)cma_src_addr(id_priv);
+ memcpy(&addr->sib_addr, &sgid, sizeof(sgid));
cma_translate_ib(addr, &id_priv->id.route.addr.dev_addr);
return 0;
}