[PATCH 3.14 74/79] iscsi-target: Avoid early conn_logout_comp for iser connections

From: Greg Kroah-Hartman
Date: Tue Mar 24 2015 - 13:50:33 EST


3.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

commit f068fbc82e7696d67b1bb8189306865bedf368b6 upstream.

This patch fixes a iser specific logout bug where early complete()
of conn->conn_logout_comp in iscsit_close_connection() was causing
isert_wait4logout() to complete too soon, triggering a use after
free NULL pointer dereference of iscsi_conn memory.

The complete() was originally added for traditional iscsi-target
when a ISCSI_LOGOUT_OP failed in iscsi_target_rx_opcode(), but given
iser-target does not wait in logout failure, this special case needs
to be avoided.

Reported-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Cc: Slava Shwartsman <valyushash@xxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/target/iscsi/iscsi_target.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -4196,11 +4196,17 @@ int iscsit_close_connection(
pr_debug("Closing iSCSI connection CID %hu on SID:"
" %u\n", conn->cid, sess->sid);
/*
- * Always up conn_logout_comp just in case the RX Thread is sleeping
- * and the logout response never got sent because the connection
- * failed.
+ * Always up conn_logout_comp for the traditional TCP case just in case
+ * the RX Thread in iscsi_target_rx_opcode() is sleeping and the logout
+ * response never got sent because the connection failed.
+ *
+ * However for iser-target, isert_wait4logout() is using conn_logout_comp
+ * to signal logout response TX interrupt completion. Go ahead and skip
+ * this for iser since isert_rx_opcode() does not wait on logout failure,
+ * and to avoid iscsi_conn pointer dereference in iser-target code.
*/
- complete(&conn->conn_logout_comp);
+ if (conn->conn_transport->transport_type == ISCSI_TCP)
+ complete(&conn->conn_logout_comp);

iscsi_release_thread_set(conn);



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