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().
Signed-off-by: Sudhakar Panneerselvam <sudhakar.panneerselvam@xxxxxxxxxx>
---
drivers/target/iscsi/iscsi_target.c | 18 +++++++++++-------
drivers/target/target_core_transport.c | 31 +++++++++++++++++++++++++------
drivers/target/target_core_xcopy.c | 3 +++
3 files changed, 39 insertions(+), 13 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 1b453629b516..93534dcc66c9 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1167,6 +1167,16 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
target_get_sess_cmd(&cmd->se_cmd, true);
+ 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,
+ ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
+ }
+
+ goto attach_cmd;
+ }
+
cmd->sense_reason = transport_lookup_cmd_lun(&cmd->se_cmd);
if (cmd->sense_reason)
goto attach_cmd;
@@ -1174,14 +1184,8 @@ int iscsit_setup_scsi_cmd(struct iscsi_conn *conn, struct iscsi_cmd *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) {
- if (cmd->sense_reason == TCM_OUT_OF_RESOURCES) {
- return iscsit_add_reject_cmd(cmd,
- ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
- }
-
+ if (cmd->sense_reason)
goto attach_cmd;
- }
if (iscsit_build_pdu_and_seq_lists(cmd, payload_length) < 0) {
return iscsit_add_reject_cmd(cmd,
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 7ea77933e64d..0fbb38254535 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1413,6 +1413,9 @@ void transport_init_se_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 @@ void transport_init_se_cmd(
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 @@ void transport_init_se_cmd(
" %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 @@ void transport_init_se_cmd(
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 @@ void transport_init_se_cmd(
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
*/
diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c
index 5f1bab37a6bf..7f9c93b5cba6 100644
--- a/drivers/target/target_core_xcopy.c
+++ b/drivers/target/target_core_xcopy.c
@@ -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;
--
1.8.3.1
