[Devel] [PATCH RHEL7 COMMIT] ms/target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.21.1.vz7.46.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.21.1.vz7.46.2
------>
commit a2d16a61f380825a9c9b25abb8d6bfc3e6ce1314
Author: Alexei Potashnik <alexei at purestorage.com>
Date:   Mon Apr 2 17:28:23 2018 +0300

    ms/target/iscsi: Fix double free of a TUR followed by a solicited NOPOUT
    
    ML: 9547308bda296b6f69876c840a0291fcfbeddbb8
    
    Make sure all non-READ SCSI commands get targ_xfer_tag initialized
    to 0xffffffff, not just WRITEs.
    
    Double-free of a TUR cmd object occurs under the following scenario:
    
    1. TUR received (targ_xfer_tag is uninitialized and left at 0)
    2. TUR status sent
    3. First unsolicited NOPIN is sent to initiator (gets targ_xfer_tag of 0)
    4. NOPOUT for NOPIN (with TTT=0) arrives
     - its ExpStatSN acks TUR status, TUR is queued for removal
     - LIO tries to find NOPIN with TTT=0, but finds the same TUR instead,
       TUR is queued for removal for the 2nd time
    
    (Drop unbalanced conditional bracket usage - nab)
    
    Signed-off-by: Alexei Potashnik <alexei at purestorage.com>
    Signed-off-by: Spencer Baugh <sbaugh at catern.com>
    Cc: <stable at vger.kernel.org> # v3.1+
    Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
    Signed-off-by: Andrei Vagin <avagin at openvz.org>
---
 drivers/target/iscsi/iscsi_target.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 35209f0a469a..ea8573e9e129 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1117,9 +1117,9 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 		cmd->cmd_flags |= ICF_NON_IMMEDIATE_UNSOLICITED_DATA;
 
 	conn->sess->init_task_tag = cmd->init_task_tag = hdr->itt;
-	if (hdr->flags & ISCSI_FLAG_CMD_READ) {
+	if (hdr->flags & ISCSI_FLAG_CMD_READ)
 		cmd->targ_xfer_tag = session_get_next_ttt(conn->sess);
-	} else if (hdr->flags & ISCSI_FLAG_CMD_WRITE)
+	else
 		cmd->targ_xfer_tag = 0xFFFFFFFF;
 	cmd->cmd_sn		= be32_to_cpu(hdr->cmdsn);
 	cmd->exp_stat_sn	= be32_to_cpu(hdr->exp_statsn);