[PATCH 3.16.y-ckt 119/142] target: Drop incorrect ABORT_TASK put for completed commands

[Luis Henriques]

3.16.7-ckt26 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

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

commit 7f54ab5ff52fb0b91569bc69c4a6bc5cac1b768d upstream.

This patch fixes a recent ABORT_TASK regression associated
with commit febe562c, where a left-over target_put_sess_cmd()
would still be called when __target_check_io_state() detected
a command has already been completed, and explicit ABORT must
be avoided.

Note commit febe562c dropped the local kref_get_unless_zero()
check in core_tmr_abort_task(), but did not drop this extra
corresponding target_put_sess_cmd() in the failure path.

So go ahead and drop this now bogus target_put_sess_cmd(),
and avoid this potential use-after-free.

Reported-by: Dan Lane <dracodan at gmail.com>
Cc: Quinn Tran <quinn.tran at qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani at qlogic.com>
Cc: Sagi Grimberg <sagig at mellanox.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Hannes Reinecke <hare at suse.de>
Cc: Andy Grover <agrover at redhat.com>
Cc: Mike Christie <mchristi at redhat.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/target/target_core_tmr.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index ebdbaaf6111d..033a59cd6c70 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -186,7 +186,6 @@ void core_tmr_abort_task(
 
 		if (!__target_check_io_state(se_cmd, se_sess, 0)) {
 			spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
-			target_put_sess_cmd(se_sess, se_cmd);
 			goto out;
 		}