The patch below does not apply to the 3.10-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 <[email protected]>.
thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ce9a9fc20a78ad1e5222fae3a83d105f2d2fb9b9 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger <[email protected]> Date: Fri, 24 Jul 2015 02:29:55 +0000 Subject: [PATCH] iser-target: Fix REJECT CM event use-after-free OOPs This patch fixes a bug in iser-target code where the REJECT CM event handler code currently performs a isert_put_conn() for the final isert_conn->kref put, while iscsi_np process context is still blocked in isert_get_login_rx(). Once isert_get_login_rx() is awoking due to login timeout, iscsi_np process context will attempt to invoke iscsi_target_login_sess_out() to cleanup iscsi_conn as expected, and calls isert_wait_conn() + isert_free_conn() which triggers the use-after-free OOPs. To address this bug, move the kref_get_unless_zero() call from isert_connected_handler() into isert_connect_request() immediately preceeding isert_rdma_accept() to ensure the CM handler cleanup paths and isert_free_conn() are always operating with two refs. Cc: Sagi Grimberg <[email protected]> Cc: <[email protected]> # v3.10+ Signed-off-by: Nicholas Bellinger <[email protected]> diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c index 771700963127..d851e1828d6f 100644 --- a/drivers/infiniband/ulp/isert/ib_isert.c +++ b/drivers/infiniband/ulp/isert/ib_isert.c @@ -775,6 +775,17 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event) ret = isert_rdma_post_recvl(isert_conn); if (ret) goto out_conn_dev; + /* + * Obtain the second reference now before isert_rdma_accept() to + * ensure that any initiator generated REJECT CM event that occurs + * asynchronously won't drop the last reference until the error path + * in iscsi_target_login_sess_out() does it's ->iscsit_free_conn() -> + * isert_free_conn() -> isert_put_conn() -> kref_put(). + */ + if (!kref_get_unless_zero(&isert_conn->kref)) { + isert_warn("conn %p connect_release is running\n", isert_conn); + goto out_conn_dev; + } ret = isert_rdma_accept(isert_conn); if (ret) @@ -836,11 +847,6 @@ isert_connected_handler(struct rdma_cm_id *cma_id) isert_info("conn %p\n", isert_conn); - if (!kref_get_unless_zero(&isert_conn->kref)) { - isert_warn("conn %p connect_release is running\n", isert_conn); - return; - } - mutex_lock(&isert_conn->mutex); if (isert_conn->state != ISER_CONN_FULL_FEATURE) isert_conn->state = ISER_CONN_UP; -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
