Patch "iscsi-target: Make TASK_REASSIGN use proper se_cmd->cmd_kref" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

    iscsi-target: Make TASK_REASSIGN use proper se_cmd->cmd_kref

to the 4.4-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-make-task_reassign-use-proper-se_cmd-cmd_kref.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Nicholas Bellinger <[email protected]>
Date: Fri, 27 Oct 2017 12:32:59 -0700
Subject: iscsi-target: Make TASK_REASSIGN use proper se_cmd->cmd_kref

From: Nicholas Bellinger <[email protected]>

commit ae072726f6109bb1c94841d6fb3a82dde298ea85 upstream.

Since commit 59b6986dbf fixed a potential NULL pointer dereference by allocating a se_tmr_req for ISCSI_TM_FUNC_TASK_REASSIGN, the se_tmr_req is currently leaked by iscsit_free_cmd() because no iscsi_cmd->se_cmd.se_tfo was associated.

To address this, treat ISCSI_TM_FUNC_TASK_REASSIGN like any other TMR and call transport_init_se_cmd() + target_get_sess_cmd() to setup iscsi_cmd->se_cmd.se_tfo with se_cmd->cmd_kref of 2.

This will ensure normal release operation once se_cmd->cmd_kref reaches zero and target_release_cmd_kref() is invoked, se_tmr_req will be released via existing target_free_cmd_mem() and core_tmr_release_req() code.

---
 drivers/target/iscsi/iscsi_target.c |   20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

@@ -1759,7 +1759,6 @@ iscsit_handle_task_mgt_cmd(struct iscsi_
 	struct iscsi_tmr_req *tmr_req;
 	struct iscsi_tm *hdr;
 	int out_of_order_cmdsn = 0, ret;
-	bool sess_ref = false;
 	u8 function, tcm_function = TMR_UNKNOWN;
 
 	hdr			= (struct iscsi_tm *) buf;

@@ -1801,18 +1800,17 @@ iscsit_handle_task_mgt_cmd(struct iscsi_
 					     buf);
 	}
 
+	transport_init_se_cmd(&cmd->se_cmd, &iscsi_ops,
+			      conn->sess->se_sess, 0, DMA_NONE,
+			      TCM_SIMPLE_TAG, cmd->sense_buffer + 2);
+
+	target_get_sess_cmd(&cmd->se_cmd, true);
+
 	/*
 	 * TASK_REASSIGN for ERL=2 / connection stays inside of
 	 * LIO-Target $FABRIC_MOD
 	 */
 	if (function != ISCSI_TM_FUNC_TASK_REASSIGN) {
-		transport_init_se_cmd(&cmd->se_cmd, &iscsi_ops,
-				      conn->sess->se_sess, 0, DMA_NONE,
-				      TCM_SIMPLE_TAG, cmd->sense_buffer + 2);
-
-		target_get_sess_cmd(&cmd->se_cmd, true);
-		sess_ref = true;
-
 		switch (function) {
 		case ISCSI_TM_FUNC_ABORT_TASK:
 			tcm_function = TMR_ABORT_TASK;

@@ -1951,12 +1949,8 @@ attach:
 	 * For connection recovery, this is also the default action for
 	 * TMR TASK_REASSIGN.
 	 */
-	if (sess_ref) {
-		pr_debug("Handle TMR, using sess_ref=true check\n");
-		target_put_sess_cmd(&cmd->se_cmd);
-	}
-
 	iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
+	target_put_sess_cmd(&cmd->se_cmd);
 	return 0;
 }
 EXPORT_SYMBOL(iscsit_handle_task_mgt_cmd);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/iscsi-target-make-task_reassign-use-proper-se_cmd-cmd_kref.patch queue-4.4/target-avoid-early-cmd_t_pre_execute-failures-during-abort_task.patch