[PATCH 015/241] target: Fix double-free of se_cmd in target_complete_tmr_failure

[Herton Ronaldo Krzesinski]

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

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

From: Nicholas Bellinger <nab at 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.

Cc: Christoph Hellwig <hch at lst.de>
Cc: Roland Dreier <roland at purestorage.com>
Cc: Andy Grover <agrover at redhat.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/target/target_core_transport.c |    1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 0981707..7879ff4 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1617,7 +1617,6 @@ static void target_complete_tmr_failure(struct work_struct *work)
 
 	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);
 }
 
 /**
-- 
1.7.9.5