As iser_pdu->desc->data_dir is not initialised when sending a PDU.
The value remains what it was when it was used last time. Thus
a PDU could be considered to have data if it previously had and
might cause segmentation fault.
For example if a pdu is a reset task management task with no data
to transfer and the pdu is previously used as a read task. Thus
it would cause fault like below:
> struct scsi_iovector *iovector_in = &task->iovector_in;
0 0x00007ffff7bcb2d1 in iser_rcv_completion (rx_desc=0x555555b79e48, iser_conn=0x555555b573a0) at iser.c:1349
1 0x00007ffff7bcb53e in iser_handle_wc (wc=0x7fffffffdc00, iser_conn=0x555555b573a0) at iser.c:1426
2 0x00007ffff7bcb685 in cq_event_handler (iser_conn=0x555555b573a0) at iser.c:1468
3 0x00007ffff7bcb81b in cq_handle (iser_conn=0x555555b573a0) at iser.c:1516
4 0x00007ffff7bc8b28 in iscsi_iser_service (iscsi=0x555555b58710, revents=1) at iser.c:118
5 0x00007ffff7bc3862 in iscsi_service (iscsi=0x555555b58710, revents=1) at socket.c:1016
6 0x00007ffff7bc3f6c in event_loop (iscsi=0x555555b58710, state=0x7fffffffe000) at sync.c:71
7 0x00007ffff7bc4605 in iscsi_task_mgmt_sync (iscsi=0x555555b58710, lun=0, function=ISCSI_TM_LUN_RESET, ritt=4294967295, rcmdsn=0) at sync.c:281
8 0x00007ffff7bc46cf in iscsi_task_mgmt_lun_reset_sync (iscsi=0x555555b58710, lun=0) at sync.c:312
9 0x000055555555500d in iscsi_lun_reset_sync (iscsi=0x555555b58710) at iscsiclient_lun_reset.c:34
10 0x0000555555555680 in main (argc=7, argv=0x7fffffffe1c8) at iscsiclient_lun_reset.c:211
Signed-off-by: Hou Pu <houpu@bytedance.com>
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