[PATCH 3/3] target: Fix parameter list length checking in MODE SELECT

[Roland Dreier <roland@kernel.org>]

From: Roland Dreier <roland@purestorage.com>

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>
---
 drivers/target/target_core_spc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 2d88f08..73c5d53 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -983,6 +983,14 @@ 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;
@@ -1007,6 +1015,11 @@ 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;
 
-- 
1.8.1.2