target: Fix parameter list length checking in MODE SELECT

An empty parameter list (length == 0) is not an error, so succeed MODE
SELECT in this case.  If the parameter list length is too small,
return the correct sense code of PARAMETER LIST LENGTH ERROR.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 803339516fb9..4cb667d720a7 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -1000,6 +1000,14 @@ static sense_reason_t spc_emulate_modeselect(struct se_cmd *cmd)
         int ret = 0;
         int i;
 
+        if (!cmd->data_length) {
+                target_complete_cmd(cmd, GOOD);
+                return 0;
+        }
+
+        if (cmd->data_length < off + 2)
+                return TCM_PARAMETER_LIST_LENGTH_ERROR;
+
         buf = transport_kmap_data_sg(cmd);
         if (!buf)
                 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
@@ -1024,6 +1032,11 @@ static sense_reason_t spc_emulate_modeselect(struct se_cmd *cmd)
         goto out;
 
 check_contents:
+        if (cmd->data_length < off + length) {
+                ret = TCM_PARAMETER_LIST_LENGTH_ERROR;
+                goto out;
+        }
+
         if (memcmp(buf + off, tbuf, length))
                 ret = TCM_INVALID_PARAMETER_LIST;