[ 20/24] target: Fix double-free of se_cmd in target_complete_tmr_failure

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit e13d5fef88c40b87c8430f8274c3a9ca32ef90bc upstream.

Fabric drivers currently expect to internally release se_cmd in the event
of a TMR failure during target_submit_tmr(), which means the immediate call
to transport_generic_free_cmd() after TFO->queue_tm_rsp() from within
target_complete_tmr_failure() workqueue context is wrong.

This is done as some fabrics expect TMR operations to be acknowledged
before releasing the descriptor, so the assumption that core is releasing
se_cmd associated TMR memory is incorrect.  This fixes a OOPs where
transport_generic_free_cmd() was being called more than once.

This bug was originally observed with tcm_qla2xxx fabric ports.

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Andy Grover <agrover@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/target_core_transport.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1553,7 +1553,6 @@ static void target_complete_tmr_failure(
 
 	se_cmd->se_tmr_req->response = TMR_LUN_DOES_NOT_EXIST;
 	se_cmd->se_tfo->queue_tm_rsp(se_cmd);
-	transport_generic_free_cmd(se_cmd, 0);
 }
 
 /**