3.19.8-ckt6 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
commit ce9a9fc20a78ad1e5222fae3a83d105f2d2fb9b9 upstream.
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 <sagig@xxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
[ kamal: backport to 3.19-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/infiniband/ulp/isert/ib_isert.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index b7350d5..bd28c48 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -686,6 +686,17 @@ 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->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)
@@ -769,11 +780,6 @@ isert_connected_handler(struct rdma_cm_id *cma_id)
isert_info("conn %p\n", isert_conn);
- if (!kref_get_unless_zero(&isert_conn->conn_kref)) {
- isert_warn("conn %p connect_release is running\n", isert_conn);
- return;
- }
-
mutex_lock(&isert_conn->conn_mutex);
if (isert_conn->state != ISER_CONN_FULL_FEATURE)
isert_conn->state = ISER_CONN_UP;
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html