From: Jack Morgenstein Date: Tue, 23 Sep 2014 09:38:26 +0000 (+0300) Subject: IB/core: Fix XRC race condition in ib_uverbs_open_qp X-Git-Tag: v3.18-rc1~7^2~1 X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=a040f95dc81986d7d55bd98a9455217522ef706d IB/core: Fix XRC race condition in ib_uverbs_open_qp In ib_uverbs_open_qp, the sharable xrc target qp is created as a "pseudo" qp and added to a list of qp's sharing the same physical QP. This is done before the "pseudo" qp is assigned a uobject. There is a race condition here if an async event arrives at the physical qp. If the event is handled after the pseudo qp is added to the list, but before it is assigned a uobject, the kernel crashes in ib_uverbs_qp_event_handler, due to trying to dereference a NULL uobject pointer. Note that simply checking for non-NULL is not enough, due to error flows in ib_uverbs_open_qp. If the failure is after assigning the uobject, but before the qp has fully been created, we still have a problem. Thus, in ib_uverbs_qp_event_handler, we test that the uobject is present, and also that it is live. Reported-by: Matthew Finlay Signed-off-by: Jack Morgenstein Signed-off-by: Or Gerlitz Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index c73b22a257fe..bb6fea12ce31 100644 --- a/drivers/infiniband/core/uverbs_main.c +++ b/drivers/infiniband/core/uverbs_main.c @@ -502,6 +502,10 @@ void ib_uverbs_qp_event_handler(struct ib_event *event, void *context_ptr) { struct ib_uevent_object *uobj; + /* for XRC target qp's, check that qp is live */ + if (!event->element.qp->uobject || !event->element.qp->uobject->live) + return; + uobj = container_of(event->element.qp->uobject, struct ib_uevent_object, uobject);