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>

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 6bf8504..055ed59 100644 (file)
--- 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;