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scsi: target: Fix NULL pointer dereference 

NULL pointer dereference happens when the following conditions are met:

1) A SCSI command is received for a non-existing LU or cdb initialization
   fails in target_setup_cmd_from_cdb().

2) Tracing is enabled.

The following call sequences lead to NULL pointer dereference:

1) iscsit_setup_scsi_cmd
     transport_lookup_cmd_lun <-- lookup fails.
          or
     target_setup_cmd_from_cdb() <-- cdb initialization fails
   iscsit_process_scsi_cmd
     iscsit_sequence_cmd
       transport_send_check_condition_and_sense
         trace_target_cmd_complete <-- NULL dereference

2) target_submit_cmd_map_sgls
     transport_lookup_cmd_lun <-- lookup fails
          or
     target_setup_cmd_from_cdb() <-- cdb initialization fails
       transport_send_check_condition_and_sense
         trace_target_cmd_complete <-- NULL dereference

In the above sequence, cmd->t_task_cdb is uninitialized which when
referenced in trace_target_cmd_complete() causes NULL pointer dereference.

The fix is to use the helper, target_cmd_init_cdb() and call it after
transport_init_se_cmd() is called, so that cmd->t_task_cdb can be
initialized and hence can be referenced in trace_target_cmd_complete().

Link: https://lore.kernel.org/r/1591559913-8388-4-git-send-email-sudhakar.panneerselvam@oracle.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Sudhakar Panneerselvam <sudhakar.panneerselvam@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Sudhakar Panneerselvam 2020-06-07 19:58:32 +00:00 committed by Martin K. Petersen
parent a36840d800
commit 9e95fb805d
3 changed files with 39 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/target/iscsi/iscsi_target.c
View File

@ -1167,13 +1167,7 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
target_get_sess_cmd(&cmd->se_cmd, true);
cmd->sense_reason = transport_lookup_cmd_lun(&cmd->se_cmd);
if (cmd->sense_reason)
goto attach_cmd;
/* only used for printks or comparing with ->ref_task_tag */
cmd->se_cmd.tag = (__force u32)cmd->init_task_tag;
cmd->sense_reason = target_setup_cmd_from_cdb(&cmd->se_cmd, hdr->cdb);
cmd->sense_reason = target_cmd_init_cdb(&cmd->se_cmd, hdr->cdb);
if (cmd->sense_reason) {
if (cmd->sense_reason == TCM_OUT_OF_RESOURCES) {
return iscsit_add_reject_cmd(cmd,
@ -1183,6 +1177,16 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
goto attach_cmd;
}
cmd->sense_reason = transport_lookup_cmd_lun(&cmd->se_cmd);
if (cmd->sense_reason)
goto attach_cmd;
/* only used for printks or comparing with ->ref_task_tag */
cmd->se_cmd.tag = (__force u32)cmd->init_task_tag;
cmd->sense_reason = target_setup_cmd_from_cdb(&cmd->se_cmd, hdr->cdb);
if (cmd->sense_reason)
goto attach_cmd;
if (iscsit_build_pdu_and_seq_lists(cmd, payload_length) < 0) {
return iscsit_add_reject_cmd(cmd,
ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);

31
drivers/target/target_core_transport.c
View File

@ -1413,6 +1413,9 @@ transport_check_alloc_task_attr(struct se_cmd *cmd)
sense_reason_t
target_cmd_init_cdb(struct se_cmd *cmd, unsigned char *cdb)
{
sense_reason_t ret;
cmd->t_task_cdb = &cmd->__t_task_cdb[0];
/*
* Ensure that the received CDB is less than the max (252 + 8) bytes
* for VARIABLE_LENGTH_CMD
@ -1421,7 +1424,8 @@ target_cmd_init_cdb(struct se_cmd *cmd, unsigned char *cdb)
pr_err("Received SCSI CDB with command_size: %d that"
" exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
scsi_command_size(cdb), SCSI_MAX_VARLEN_CDB_SIZE);
return TCM_INVALID_CDB_FIELD;
ret = TCM_INVALID_CDB_FIELD;
goto err;
}
/*
* If the received CDB is larger than TCM_MAX_COMMAND_SIZE,
@ -1436,10 +1440,10 @@ target_cmd_init_cdb(struct se_cmd *cmd, unsigned char *cdb)
" %u > sizeof(cmd->__t_task_cdb): %lu ops\n",
scsi_command_size(cdb),
(unsigned long)sizeof(cmd->__t_task_cdb));
return TCM_OUT_OF_RESOURCES;
ret = TCM_OUT_OF_RESOURCES;
goto err;
}
}
} else
cmd->t_task_cdb = &cmd->__t_task_cdb[0];
/*
* Copy the original CDB into cmd->
*/
@ -1447,6 +1451,15 @@ target_cmd_init_cdb(struct se_cmd *cmd, unsigned char *cdb)
trace_target_sequencer_start(cmd);
return 0;
err:
/*
* Copy the CDB here to allow trace_target_cmd_complete() to
* print the cdb to the trace buffers.
*/
memcpy(cmd->t_task_cdb, cdb, min(scsi_command_size(cdb),
(unsigned int)TCM_MAX_COMMAND_SIZE));
return ret;
}
EXPORT_SYMBOL(target_cmd_init_cdb);
@ -1456,8 +1469,6 @@ target_setup_cmd_from_cdb(struct se_cmd *cmd, unsigned char *cdb)
struct se_device *dev = cmd->se_dev;
sense_reason_t ret;
target_cmd_init_cdb(cmd, cdb);
ret = dev->transport->parse_cdb(cmd);
if (ret == TCM_UNSUPPORTED_SCSI_OPCODE)
pr_warn_ratelimited("%s/%s: Unsupported SCSI Opcode 0x%02x, sending CHECK_CONDITION.\n",
@ -1621,6 +1632,14 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
*/
if (flags & TARGET_SCF_BIDI_OP)
se_cmd->se_cmd_flags |= SCF_BIDI;
rc = target_cmd_init_cdb(se_cmd, cdb);
if (rc) {
transport_send_check_condition_and_sense(se_cmd, rc, 0);
target_put_sess_cmd(se_cmd);
return 0;
}
/*
* Locate se_lun pointer and attach it to struct se_cmd
*/

3
drivers/target/target_core_xcopy.c
View File

@ -526,6 +526,9 @@ static int target_xcopy_setup_pt_cmd(
}
cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
if (target_cmd_init_cdb(cmd, cdb))
return -EINVAL;
cmd->tag = 0;
if (target_setup_cmd_from_cdb(cmd, cdb))
return -EINVAL;