scsi: megaraid_sas: MR_TargetIdToLdGet u8 to u16 and avoid invalid raid-map access

scsi: megaraid_sas: MR_TargetIdToLdGet u8 to u16 and avoid invalid raid-map access

Change MR_TargetIdToLdGet return type from u8 to u16.

ld id range check is added at two places in this patch -
@megasas_build_ldio_fusion and @megasas_build_ld_nonrw_fusion.  Previous
driver code used different data type for lds TargetId returned from
MR_TargetIdToLdGet.  Prior to this change, above two functions was
safeguarded due to function always return u8 and maximum value of ld id
returned was 255.

In below check, fw_supported_vd_count as of today is 64 or 256 and valid
range to support is either 0-63 or 0-255. Ideally want to filter
accessing raid map for ld ids which are not valid. With the u16 change,
invalid ld id value is 0xFFFF and we will see kernel panic due to random
memory access in MR_LdRaidGet.  The changes will ensure we do not call
MR_LdRaidGet if ld id is beyond size of ldSpanMap array.

               if (ld < instance->fw_supported_vd_count)

>From firmware perspective,ld id 0xFF is invalid and even though current
driver code forward such command, firmware fails with target not
available.

ld target id issue occurs mainly whenever driver loops to populate raid
map (ea. MR_ValidateMapInfo).  These are the only two places where we
may see out of range target ids and wants to protect raid map access
based on range provided by Firmware API.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>