TCM buffer length doesn't necessarily equal 8 + ADDITIONAL LENGTH which
might be considered an underflow in case of Data-In size being greater than
8 + ADDITIONAL LENGTH. So truncate buffer length to prevent underflow.

Signed-off-by: Aleksandr Miloserdov <redacted>
Reviewed-by: Roman Bolshakov <redacted>
---
  drivers/target/target_core_pr.c | 15 +++++++++++----
  1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 14db5e568f22..a13140e95b47 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c

@@ -3739,6 +3739,7 @@ core_scsi3_pri_read_keys(struct se_cmd *cmd)
  	spin_unlock(&dev->t10_pr.registration_lock);
  
  	put_unaligned_be32(add_len, &buf[4]);
+	target_set_cmd_data_length(cmd, 8 + add_len);
  
  	transport_kunmap_data_sg(cmd);
  

@@ -3757,7 +3758,7 @@ core_scsi3_pri_read_reservation(struct se_cmd *cmd)
  	struct t10_pr_registration *pr_reg;
  	unsigned char *buf;
  	u64 pr_res_key;
-	u32 add_len = 16; /* Hardcoded to 16 when a reservation is held. */
+	u32 add_len = 0;
  
  	if (cmd->data_length < 8) {
  		pr_err("PRIN SA READ_RESERVATIONS SCSI Data Length: %u"

@@ -3775,8 +3776,9 @@ core_scsi3_pri_read_reservation(struct se_cmd *cmd)
  	pr_reg = dev->dev_pr_res_holder;
  	if (pr_reg) {
  		/*
-		 * Set the hardcoded Additional Length
+		 * Set the Additional Length to 16 when a reservation is held
  		 */
+		add_len = 16;
  		put_unaligned_be32(add_len, &buf[4]);
  
  		if (cmd->data_length < 22)

@@ -3812,6 +3814,8 @@ core_scsi3_pri_read_reservation(struct se_cmd *cmd)
  			  (pr_reg->pr_res_type & 0x0f);
  	}
  
+	target_set_cmd_data_length(cmd, 8 + add_len);
+
  err:
  	spin_unlock(&dev->dev_reservation_lock);
  	transport_kunmap_data_sg(cmd);

@@ -3830,7 +3834,7 @@ core_scsi3_pri_report_capabilities(struct se_cmd *cmd)
  	struct se_device *dev = cmd->se_dev;
  	struct t10_reservation *pr_tmpl = &dev->t10_pr;
  	unsigned char *buf;
-	u16 add_len = 8; /* Hardcoded to 8. */
+	u16 len = 8; /* Hardcoded to 8. */
  
  	if (cmd->data_length < 6) {
  		pr_err("PRIN SA REPORT_CAPABILITIES SCSI Data Length:"

@@ -3842,7 +3846,7 @@ core_scsi3_pri_report_capabilities(struct se_cmd *cmd)
  	if (!buf)
  		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  
-	put_unaligned_be16(add_len, &buf[0]);
+	put_unaligned_be16(len, &buf[0]);
  	buf[2] |= 0x10; /* CRH: Compatible Reservation Hanlding bit. */
  	buf[2] |= 0x08; /* SIP_C: Specify Initiator Ports Capable bit */
  	buf[2] |= 0x04; /* ATP_C: All Target Ports Capable bit */

@@ -3871,6 +3875,8 @@ core_scsi3_pri_report_capabilities(struct se_cmd *cmd)
  	buf[4] |= 0x02; /* PR_TYPE_WRITE_EXCLUSIVE */
  	buf[5] |= 0x01; /* PR_TYPE_EXCLUSIVE_ACCESS_ALLREG */
  
+	target_set_cmd_data_length(cmd, len);
+
  	transport_kunmap_data_sg(cmd);
  
  	return 0;

@@ -4031,6 +4037,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
  	 * Set ADDITIONAL_LENGTH
  	 */
  	put_unaligned_be32(add_len, &buf[4]);
+	target_set_cmd_data_length(cmd, 8 + add_len);
  
  	transport_kunmap_data_sg(cmd);