linux-kernel - [PATCH 4.2.y-ckt 70/98] target: Drop incorrect ABORT

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Message-Id: <1458084692-23100-71-git-send-email-kamal@canonical.com>
Date:	Tue, 15 Mar 2016 16:31:04 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Quinn Tran <quinn.tran@...gic.com>,
	Himanshu Madhani <himanshu.madhani@...gic.com>,
	Sagi Grimberg <sagig@...lanox.com>,
	Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
	Andy Grover <agrover@...hat.com>,
	Mike Christie <mchristi@...hat.com>,
	Nicholas Bellinger <nab@...ux-iscsi.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 70/98] target: Drop incorrect ABORT_TASK put for completed commands

4.2.8-ckt6 -stable review patch.  If anyone has any objections, please let me know.

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

From: Nicholas Bellinger <nab@...ux-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@...il.com>
Cc: Quinn Tran <quinn.tran@...gic.com>
Cc: Himanshu Madhani <himanshu.madhani@...gic.com>
Cc: Sagi Grimberg <sagig@...lanox.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Hannes Reinecke <hare@...e.de>
Cc: Andy Grover <agrover@...hat.com>
Cc: Mike Christie <mchristi@...hat.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.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 88029cc..46b1991 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -177,7 +177,6 @@ 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_cmd);
 			goto out;
 		}
 		list_del_init(&se_cmd->se_cmd_list);
-- 
2.7.0