[PATCH-3.14.y] target: Drop incorrect ABORT_TASK put for completed commands

[PATCH-3.14.y] target: Drop incorrect ABORT_TASK put for completed commands

[Nicholas A. Bellinger]

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

Hi Greg-KH & stable team,

Here's the updated v3.14.y backport for the target patch that
failed to apply today.  It's a oneliner, and should apply up
to and including v4.0, before target_put_sess_cmd() lost it's
extra arguement in >= v4.1.

Please apply at your earliest convenience.

Thank you,

--nab

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

commit 7ddbc0a70222eb820c3abc2085894b695c7f7665 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@gmail.com>
Cc: Quinn Tran <quinn.tran@qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani@qlogic.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 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 47a90d6..77c1438 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -181,7 +181,6 @@ 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;
 		}
 
-- 
1.8.5.3

Re: [PATCH-3.14.y] target: Drop incorrect ABORT_TASK put for completed commands

[Greg-KH]

On Tue, Mar 15, 2016 at 04:39:11AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Hi Greg-KH & stable team,
> 
> Here's the updated v3.14.y backport for the target patch that
> failed to apply today.  It's a oneliner, and should apply up
> to and including v4.0, before target_put_sess_cmd() lost it's
> extra arguement in >= v4.1.
> 
> Please apply at your earliest convenience.
> 
> Thank you,
> 
> --nab
> 
> -------------------------------------------------------------
> 
> commit 7ddbc0a70222eb820c3abc2085894b695c7f7665 upstream.

There is no such object in Linus's tree :(

Don't you mean 7f54ab5ff52fb0b91569bc69c4a6bc5cac1b768d ?

Please be more careful...

greg k-h