The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From fce50a2fa4e9c6e103915c351b6d4a98661341d6 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> Date: Thu, 29 Jun 2017 22:21:31 -0700 Subject: [PATCH] iser-target: Avoid isert_conn->cm_id dereference in isert_login_recv_done This patch fixes a NULL pointer dereference in isert_login_recv_done() of isert_conn->cm_id due to isert_cma_handler() -> isert_connect_error() resetting isert_conn->cm_id = NULL during a failed login attempt. As per Sagi, we will always see the completion of all recv wrs posted on the qp (given that we assigned a ->done handler), this is a FLUSH error completion, we just don't get to verify that because we deref NULL before. The issue here, was the assumption that dereferencing the connection cm_id is always safe, which is not true since: commit 4a579da2586bd3b79b025947ea24ede2bbfede62 Author: Sagi Grimberg <sagig@xxxxxxxxxxxx> Date: Sun Mar 29 15:52:04 2015 +0300 iser-target: Fix possible deadlock in RDMA_CM connection error As I see it, we have a direct reference to the isert_device from isert_conn which is the one-liner fix that we actually need like we do in isert_rdma_read_done() and isert_rdma_write_done(). Reported-by: Andrea Righi <righi.andrea@xxxxxxxxx> Tested-by: Andrea Righi <righi.andrea@xxxxxxxxx> Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 3.10+ Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c index fcbed35e95a8..0e662656ef42 100644 --- a/drivers/infiniband/ulp/isert/ib_isert.c +++ b/drivers/infiniband/ulp/isert/ib_isert.c @@ -1452,7 +1452,7 @@ static void isert_login_recv_done(struct ib_cq *cq, struct ib_wc *wc) { struct isert_conn *isert_conn = wc->qp->qp_context; - struct ib_device *ib_dev = isert_conn->cm_id->device; + struct ib_device *ib_dev = isert_conn->device->ib_device; if (unlikely(wc->status != IB_WC_SUCCESS)) { isert_print_wc(wc, "login recv");