target/iscsi: Fix a race condition in iscsit_add_reject_from_cmd()

[ 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>

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index bb73401..8a4092c 100644 (file)
--- 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);
        }