IB/core: If the MGID/MLID pair is not on the list return an error

A list of MGID/MLID pairs is built when doing a multicast attach.  When
the multicast detach is called, the list is searched, and regardless of
the search outcome, the driver detach is called.

If an MGID/MLID pair is not on the list, driver detach should not be
called, and an error should be returned.  Calling the driver without
removing an MGID/MLID pair from the list can leave the core and driver
out of sync.

Fixes: f4e401562c11 ("IB/uverbs: track multicast group membership for userspace QPs")
Cc: stable@vger.kernel.org
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 7a4a10ef8b49f7e9939d390193708ea37c84b4fb..cb3c426c0dad888410caa481de3b7e57ff13c650 100644 (file)
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -2658,6 +2658,7 @@ ssize_t ib_uverbs_detach_mcast(struct ib_uverbs_file *file,
        struct ib_qp                 *qp;
        struct ib_uverbs_mcast_entry *mcast;
        int                           ret = -EINVAL;
+       bool                          found = false;
 
        if (copy_from_user(&cmd, buf, sizeof cmd))
                return -EFAULT;
@@ -2669,18 +2670,22 @@ ssize_t ib_uverbs_detach_mcast(struct ib_uverbs_file *file,
        obj = container_of(qp->uobject, struct ib_uqp_object, uevent.uobject);
        mutex_lock(&obj->mcast_lock);
 
-       ret = ib_detach_mcast(qp, (union ib_gid *) cmd.gid, cmd.mlid);
-       if (ret)
-               goto out_put;
-
        list_for_each_entry(mcast, &obj->mcast_list, list)
                if (cmd.mlid == mcast->lid &&
                    !memcmp(cmd.gid, mcast->gid.raw, sizeof mcast->gid.raw)) {
                        list_del(&mcast->list);
                        kfree(mcast);
+                       found = true;
                        break;
                }
 
+       if (!found) {
+               ret = -EINVAL;
+               goto out_put;
+       }
+
+       ret = ib_detach_mcast(qp, (union ib_gid *)cmd.gid, cmd.mlid);
+
 out_put:
        mutex_unlock(&obj->mcast_lock);
        uobj_put_obj_read(qp);