CVE-2022-21546

In the Linux kernel, the following vulnerability has been resolved:

scsi: target: Fix WRITE_SAME No Data Buffer crash

In newer version of the SBC specs, we have a NDOB bit that indicates there is no data buffer that gets written out. If this bit is set using commands like "sgwritesame --ndob" we will crash in targetcoreiblock/file's executewritesame handlers when we go to access the secmd->tdata_sg because its NULL.

This patch adds a check for the NDOB bit in the common WRITE SAME code because we don't support it. And, it adds a check for zero SG elements in each handler in case the initiator tries to send a normal WRITE SAME with no data buffer.