[PATCH 09/11] target/iscsi: Fix a race condition in iscsit_add_reject_from_cmd()

From: Bart Van Assche <bart.vanassche@wdc.com>
To: target-devel@vger.kernel.org
Subject: [PATCH 09/11] target/iscsi: Fix a race condition in iscsit_add_reject_from_cmd()
Date: Tue, 31 Oct 2017 18:03:17 +0000	[thread overview]
Message-ID: <20171031180319.19258-10-bart.vanassche@wdc.com> (raw)

Avoid that cmd->se_cmd.se_tfo is read after a command has already been
freed.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Mike Christie <mchristi@redhat.com>
---
 drivers/target/iscsi/iscsi_target.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 91fbada7cdc2..541f66a875fc 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -833,6 +833,7 @@ static int iscsit_add_reject_from_cmd(
 	unsigned char *buf)
 {
 	struct iscsi_conn *conn;
+	const bool do_put = cmd->se_cmd.se_tfo != NULL;
 
 	if (!cmd->conn) {
 		pr_err("cmd->conn is NULL for ITT: 0x%08x\n",
@@ -863,7 +864,7 @@ static int iscsit_add_reject_from_cmd(
 	 * Perform the kref_put now if se_cmd has already been setup by
 	 * scsit_setup_scsi_cmd()
 	 */
-	if (cmd->se_cmd.se_tfo != NULL) {
+	if (do_put) {
 		pr_debug("iscsi reject: calling target_put_sess_cmd >>>>>>\n");
 		target_put_sess_cmd(&cmd->se_cmd);
 	}
-- 
2.14.2

