[PATCH 4.4 080/115] target/iscsi: Fix a race condition in iscsit_add_reject_from_cmd()

Greg Kroah-Hartman
2017-12-18T17:59:36Z

From: Bart Van Assche <bart.vanassche@wdc.com>

[ Upstream commit cfe2b621bb18d86e93271febf8c6e37622da2d14 ]

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: Christoph Hellwig <hch@lst.de>
Cc: Mike Christie <mchristi@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/target/iscsi/iscsi_target.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -674,6 +674,7 @@ 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",
@@ -704,7 +705,7 @@ 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);
}