[PATCH 4.4 49/50] target: Drop incorrect ABORT_TASK put for completed commands

From: Greg Kroah-Hartman
Date: Mon Mar 14 2016 - 13:55:30 EST


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

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

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

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@xxxxxxxxx>
Cc: Quinn Tran <quinn.tran@xxxxxxxxxx>
Cc: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Andy Grover <agrover@xxxxxxxxxx>
Cc: Mike Christie <mchristi@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- 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);