This is a note to let you know that I've just added the patch titled
iscsi-target: Fix TMR reference leak during session shutdown
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iscsi-target-fix-tmr-reference-leak-during-session-shutdown.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From efb2ea770bb3b0f40007530bc8b0c22f36e1c5eb Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date: Thu, 23 Mar 2017 17:19:24 -0700
Subject: iscsi-target: Fix TMR reference leak during session shutdown
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
commit efb2ea770bb3b0f40007530bc8b0c22f36e1c5eb upstream.
This patch fixes a iscsi-target specific TMR reference leak
during session shutdown, that could occur when a TMR was
quiesced before the hand-off back to iscsi-target code
via transport_cmd_check_stop_to_fabric().
The reference leak happens because iscsit_free_cmd() was
incorrectly skipping the final target_put_sess_cmd() for
TMRs when transport_generic_free_cmd() returned zero because
the se_cmd->cmd_kref did not reach zero, due to the missing
se_cmd assignment in original code.
The result was iscsi_cmd and it's associated se_cmd memory
would be freed once se_sess->sess_cmd_map where released,
but the associated se_tmr_req was leaked and remained part
of se_device->dev_tmr_list.
This bug would manfiest itself as kernel paging request
OOPsen in core_tmr_lun_reset(), when a left-over se_tmr_req
attempted to dereference it's se_cmd pointer that had
already been released during normal session shutdown.
To address this bug, go ahead and treat ISCSI_OP_SCSI_CMD
and ISCSI_OP_SCSI_TMFUNC the same when there is an extra
se_cmd->cmd_kref to drop in iscsit_free_cmd(), and use
op_scsi to signal __iscsit_free_cmd() when the former
needs to clear any further iscsi related I/O state.
Reported-by: Rob Millner <rlm@xxxxxxxxxxxxx>
Cc: Rob Millner <rlm@xxxxxxxxxxxxx>
Reported-by: Chu Yuan Lin <cyl@xxxxxxxxx>
Cc: Chu Yuan Lin <cyl@xxxxxxxxx>
Tested-by: Chu Yuan Lin <cyl@xxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/target/iscsi/iscsi_target_util.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -735,21 +735,23 @@ void iscsit_free_cmd(struct iscsi_cmd *c
{
struct se_cmd *se_cmd = NULL;
int rc;
+ bool op_scsi = false;
/*
* Determine if a struct se_cmd is associated with
* this struct iscsi_cmd.
*/
switch (cmd->iscsi_opcode) {
case ISCSI_OP_SCSI_CMD:
- se_cmd = &cmd->se_cmd;
- __iscsit_free_cmd(cmd, true, shutdown);
+ op_scsi = true;
/*
* Fallthrough
*/
case ISCSI_OP_SCSI_TMFUNC:
- rc = transport_generic_free_cmd(&cmd->se_cmd, shutdown);
- if (!rc && shutdown && se_cmd && se_cmd->se_sess) {
- __iscsit_free_cmd(cmd, true, shutdown);
+ se_cmd = &cmd->se_cmd;
+ __iscsit_free_cmd(cmd, op_scsi, shutdown);
+ rc = transport_generic_free_cmd(se_cmd, shutdown);
+ if (!rc && shutdown && se_cmd->se_sess) {
+ __iscsit_free_cmd(cmd, op_scsi, shutdown);
target_put_sess_cmd(se_cmd);
}
break;
Patches currently in stable-queue which might be from nab@xxxxxxxxxxxxxxx are
queue-4.9/tcmu-fix-wrongly-calculating-of-the-base_command_size.patch
queue-4.9/iscsi-target-drop-work-around-for-legacy-globalsan-initiator.patch
queue-4.9/iscsi-target-fix-tmr-reference-leak-during-session-shutdown.patch
queue-4.9/target-avoid-mappedlun-symlink-creation-during-lun-shutdown.patch
queue-4.9/tcmu-fix-possible-overwrite-of-t_data_sg-s-last-iov.patch
queue-4.9/tcmu-skip-data-out-blocks-before-gathering-data-in-buffer-for-bidi-case.patch