RDMA/ucma.c: Fix for events with wrong context on iWARP

It is possible for asynchronous RDMA_CM_EVENT_ESTABLISHED events to be
generated with ctx->uid == 0, because ucma_set_event_context() copies
ctx->uid to the event structure outside of ctx->file->mut.  This leads
to a crash in the userspace library, since it gets a bogus event.

Fix this by taking the mutex a bit earlier in ucma_event_handler.

Signed-off-by: Tatyana Nikolova <Tatyana.E.Nikolova@intel.com>
Signed-off-by: Sean Hefty <Sean.Hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 6bf850422895..055ed59838dc 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -267,6 +267,7 @@ static int ucma_event_handler(struct rdma_cm_id *cm_id,
         if (!uevent)
                 return event->event == RDMA_CM_EVENT_CONNECT_REQUEST;
 
+        mutex_lock(&ctx->file->mut);
         uevent->cm_id = cm_id;
         ucma_set_event_context(ctx, event, uevent);
         uevent->resp.event = event->event;
@@ -277,7 +278,6 @@ static int ucma_event_handler(struct rdma_cm_id *cm_id,
                 ucma_copy_conn_event(&uevent->resp.param.conn,
                                      &event->param.conn);
 
-        mutex_lock(&ctx->file->mut);
         if (event->event == RDMA_CM_EVENT_CONNECT_REQUEST) {
                 if (!ctx->backlog) {
                         ret = -ENOMEM;