scsi: target: core: Add cmd length set before cmd complete

BugLink: https://bugs.launchpad.net/bugs/1919492
[ Upstream commit 1c73e0c5e54d5f7d77f422a10b03ebe61eaed5ad ]

TCM doesn't properly handle underflow case for service actions. One way to
prevent it is to always complete command with
target_complete_cmd_with_length(), however it requires access to data_sg,
which is not always available.

This change introduces target_set_cmd_data_length() function which allows
to set command data length before completing it.

Link: https://lore.kernel.org/r/20210209072202.41154-2-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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index fca4bd079d02cdb9e41fcb468f5f5b621f0c5089..8a4d58fdc9fe2a16cb589cd2652583bec4496f09 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -879,11 +879,9 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
 }
 EXPORT_SYMBOL(target_complete_cmd);
 
-void target_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int length)
+void target_set_cmd_data_length(struct se_cmd *cmd, int length)
 {
-       if ((scsi_status == SAM_STAT_GOOD ||
-            cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL) &&
-           length < cmd->data_length) {
+       if (length < cmd->data_length) {
                if (cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
                        cmd->residual_count += cmd->data_length - length;
                } else {
@@ -893,6 +891,15 @@ void target_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int len
 
                cmd->data_length = length;
        }
+}
+EXPORT_SYMBOL(target_set_cmd_data_length);
+
+void target_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int length)
+{
+       if (scsi_status == SAM_STAT_GOOD ||
+           cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL) {
+               target_set_cmd_data_length(cmd, length);
+       }
 
        target_complete_cmd(cmd, scsi_status);
 }

diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 6336780d83a7525085e3fdc86d209e179af37abc..ce2fba49c95daeb576bd146591806dce6276169f 100644 (file)
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -72,6 +72,7 @@ int   transport_backend_register(const struct target_backend_ops *);
 void   target_backend_unregister(const struct target_backend_ops *);
 
 void   target_complete_cmd(struct se_cmd *, u8);
+void   target_set_cmd_data_length(struct se_cmd *, int);
 void   target_complete_cmd_with_length(struct se_cmd *, u8, int);
 
 void   transport_copy_sense_to_cmd(struct se_cmd *, unsigned char *);