scsi: target: core: Prevent underflow for service actions

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.

Link: https://lore.kernel.org/r/20210209072202.41154-3-a.miloserdov@yadro.com
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Aleksandr Miloserdov <a.miloserdov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 14db5e5..d4cc43a 100644 (file)
--- 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);