Several places were not checking that the parameter list length
was large enough, and thus accessing invalid memory.  Zero-length
parameter lists are just a special case of this.

Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
 drivers/target/target_core_alua.c   |    7 +++++++
 drivers/target/target_core_iblock.c |   17 +++++++++++++++--
 drivers/target/target_core_pr.c     |    8 ++++++++
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/target/target_core_alua.c 
b/drivers/target/target_core_alua.c
index 9179997..41641ba 100644
--- a/drivers/target/target_core_alua.c
+++ b/drivers/target/target_core_alua.c
@@ -218,6 +218,13 @@ int target_emulate_set_target_port_groups(struct se_cmd 
*cmd)
                cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                return -EINVAL;
        }
+       if (cmd->data_length < 4) {
+               pr_warn("SET TARGET PORT GROUPS parameter list length %u too"
+                       " small\n", cmd->data_length);
+               cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
+               return -EINVAL;
+       }
+
        buf = transport_kmap_data_sg(cmd);
 
        /*
diff --git a/drivers/target/target_core_iblock.c 
b/drivers/target/target_core_iblock.c
index 76db75e..9ba4954 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -325,17 +325,30 @@ static int iblock_execute_unmap(struct se_cmd *cmd)
        struct iblock_dev *ibd = dev->dev_ptr;
        unsigned char *buf, *ptr = NULL;
        sector_t lba;
-       int size = cmd->data_length;
+       int size;
        u32 range;
        int ret = 0;
        int dl, bd_dl;
 
+       if (cmd->data_length < 8) {
+               pr_warn("UNMAP parameter list length %u too small\n",
+                       cmd->data_length);
+               cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
+               return -EINVAL;
+       }
+
        buf = transport_kmap_data_sg(cmd);
 
        dl = get_unaligned_be16(&buf[0]);
        bd_dl = get_unaligned_be16(&buf[2]);
 
-       size = min(size - 8, bd_dl);
+       size = cmd->data_length - 8;
+       if (bd_dl > size)
+               pr_warn("UNMAP parameter list length %u too small, ignoring 
bd_dl %u\n",
+                       cmd->data_length, bd_dl);
+       else
+               size = bd_dl;
+
        if (size / 16 > 
dev->se_sub_dev->se_dev_attrib.max_unmap_block_desc_count) {
                cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
                ret = -EINVAL;
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 1e94650..956c84c 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -1540,6 +1540,14 @@ static int core_scsi3_decode_spec_i_port(
        tidh_new->dest_local_nexus = 1;
        list_add_tail(&tidh_new->dest_list, &tid_dest_list);
 
+       if (cmd->data_length < 28) {
+               pr_warn("SPC-PR: Received PR OUT parameter list"
+                       " length too small: %u\n", cmd->data_length);
+               cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
+               ret = -EINVAL;
+               goto out;
+       }
+
        buf = transport_kmap_data_sg(cmd);
        /*
         * For a PERSISTENT RESERVE OUT specify initiator ports payload,
-- 
1.7.1


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